Transforming growth factor beta (TGF-beta) in inflammation: a cause and a cure

Induction of RANTES by TWEAK/Fn14 Interaction in Human Keratinocytes

TNF-like weak inducer of apoptosis (TWEAK), a member of the tumor necrosis factor (TNF) family, is a multifunctional cytokine that regulate cellular proliferation, angiogenesis, inflammation, and apoptosis. In this study, we investigated the effect of TWEAK on human keratinocytes. Primary cultured normal human keratinocytes constitutively expressed a TWEAK receptor, fibroblast growth factor-inducible 14 (Fn14), and produced regulated on activation, normal T expressed and secreted (RANTES) upon TWEAK stimulation in a concentration-dependent manner. The TWEAK-induced RANTES production was abrogated by anti-Fn14 antibody, and synergistically augmented by simultaneous stimulation with transforming growth factor-beta. In addition, human keratinocytes differentiated in vitro with high Ca(2+)-containing medium showed enhanced production of RANTES upon TWEAK stimulation. Furthermore, TWEAK induced rapid phosphorylation of IkappaB-alpha in human keratinocytes. Collectively, TWEAK acts on human keratinocytes as an inducer of RANTES via Fn14. Because RANTES has been implicated in inflammation, TWEAK/Fn14 interaction in human keratinocytes may be involved in the pathophysiology of inflammatory skin disorders.

Effect of neutralizing transforming growth factor beta1 on the immune response against Mycobacterium tuberculosis in guinea pigs

Transforming growth factor beta (TGF-beta) is a cytokine which has been shown to suppress the antimycobacterial immune responses of humans and experimental animals. In this study, the contributions of TGF-beta to cytokine production in vivo were investigated by using the established guinea pig model of tuberculous pleurisy. Mycobacterium bovis BCG-vaccinated guinea pigs were injected intrapleurally with heat-killed virulent Mycobacterium tuberculosis. Eight days following induction of an antigen-specific pleural effusion, guinea pigs were injected intrapleurally with anti-TGF-beta1 or isotype control antibody. The following day, pleural exudates were removed, and the fluid volume and characteristics of the infiltrating cells were determined. Pleural fluid was analyzed for total interferon (IFN) and tumor necrosis factor (TNF) protein levels by using appropriate bioassays. RNA from pleural effusion cells was examined to determine TGF-beta1, TNF-alpha, IFN-gamma, and interleukin-8 mRNA levels by using real-time PCR. Proliferative responses of pleural effusion lymphocytes were examined in response to concanavalin A and purified protein derivative (PPD) in vitro. Treatment with anti-TGF-beta1 resulted in decreased pleural fluid volume and decreased cell numbers in the pleural space along with an increased percentage of lymphocytes and a decreased percentage of neutrophils. The bioactive TNF protein levels in pleural fluid were increased in guinea pigs treated with anti-TGF-beta1, while the bioactive IFN protein concentrations were not altered. Expression of TGF-beta1 and TNF-alpha mRNA was significantly increased following TGF-beta1 neutralization. Finally, PPD-induced proliferative responses of pleural cells from anti-TGF-beta1-treated animals were significantly enhanced. Thus, TGF-beta1 may be involved in the resolution of this local, mycobacterial antigen-specific inflammatory response.

Characterization of a neuraminidase-deficient influenza a virus as a potential gene delivery vector and a live vaccine

We recently identified a packaging signal in the neuraminidase (NA) viral RNA (vRNA) segment of an influenza A virus, allowing us to produce a mutant virus [GFP(NA)-Flu] that lacks most of the NA open reading frame but contains instead the gene encoding green fluorescent protein (GFP). To exploit the expanding knowledge of vRNA packaging signals to establish influenza virus vectors for the expression of foreign genes, we studied the replicative properties of this virus in cell culture and mice. Compared to wild-type virus, GFP(NA)-Flu was highly attenuated in normal cultured cells but was able to grow to a titer of >10(6) PFU/ml in a mutant cell line expressing reduced levels of sialic acid on the cell surface. GFP expression from this virus was stable even after five passages in the latter cells. In intranasally infected mice, GFP was detected in the epithelial cells of nasal mucosa, bronchioles, and alveoli for up to 4 days postinfection. We attribute the attenuated growth of GFP(NA)-Flu to virion aggregation at the surface of bronchiolar epithelia. In studies to test the potential of this mutant as a live attenuated influenza vaccine, all mice vaccinated with >/==" BORDER="0">10(5) PFU of GFP(NA)-Flu survived when challenged with lethal doses of the parent virus. These results suggest that influenza virus could be a useful vector for expressing foreign genes and that a sialidase-deficient virus may offer an alternative to the live influenza vaccines recently approved for human use.

Mediation of transforming growth factor-beta(1)-stimulated matrix contraction by fibroblasts: a role for connective tissue growth factor in contractile scarring

Excessive cell-mediated tissue contraction after injury can lead to morbid contractile scarring in the body. In the eye this can cause blindness because of posterior capsule opacification, proliferative vitroretinopathy, failure of glaucoma filtration surgery, and corneal haze. During repair, transforming growth factor (TGF)-beta and connective tissue growth factor (CTGF) genes are co-ordinately expressed. Although TGF-beta and CTGF stimulate new matrix deposition, their role and regulation during contractile scarring is unknown. In this study, an in vitro model of collagen matrix contraction culminating from tractional forces generated by fibroblasts showed that both TGF-beta(1) and CTGF-stimulated contraction. Using a specific anti-sense oligodeoxynucleotide to CTGF the procontractile activity of TGF-beta(1) was found to be mediated by CTGF. During contraction fibroblasts produced similar levels of matrix metalloproteinases (MMPs)-2 and -9 with TGF-beta(1) or CTGF and a modest increase in MMP-1 with CTGF only (indicated by zymography and enzyme-linked immunosorbent assay). The requirement of MMPs for contraction was demonstrated using a broad-spectrum synthetic inhibitor. This study demonstrates a new function for CTGF in mediating matrix contraction by fibroblasts involving MMPs and suggests a novel regulatory mechanism for TGF-beta-stimulated contraction. Inhibition of CTGF activity or gene transcription could be a suitable target for anti-scarring therapies.

Cytokines, chemokines, and cell adhesion molecules in inflammatory myopathies

The inflammatory myopathies include dermatomyositis (DM), polymyositis (PM), and sporadic inclusion-body myositis (s-IBM). In DM, the main immune effector response appears to be humoral and directed against the microvasculature, whereas in both PM and s-IBM, cytotoxic CD8+ T cells and macrophages invade and eventually destroy nonnecrotic muscle fibers expressing major histocompatibility complex class I. The need for more specific and safer therapies in inflammatory myopathies has prompted researchers to better decipher the molecular events associated with inflammation and muscle fiber loss in these diseases. The complex specific migration of leukocyte subsets to target tissues requires a coordinated series of events, namely activation of leukocytes, adhesion to the vascular endothelium, and migration. Cell adhesion molecules (CAM) and chemokines play a major role in this multistep process. In addition, cytokines by stimulating CAM expression and orchestrating T-cell differentiation also influence the immune response. This review focuses on recent advances in defining the molecular events involved in leukocyte trafficking in inflammatory myopathies. Specific topics include a concise summary of clinical features, pathological findings and immunopathology observed in inflammatory myopathies, background information about cytokines, chemokines and cell adhesion molecules, and the expression of these molecules in inflammatory myopathies.

TGF-β1 increases microbial clearance but worsens lung injury during Escherichia coli pneumonia in rats

We investigated the effects of either intravenous (IV) or intrabronchial (IB) treatment with transforming growth factor beta1 (TGF-beta1) during bacterial pneumonia in rats. Immediately following IB Escherichia coli inoculation (T0), animals (n=270) were randomized to receive a single treatment with human recombinant TGF-beta1 either via IV or IB, or via both IV and IB routes, or to receive placebo (human serum albumin, HSA) only. Blood and lung analysis was done at 6 and 168 h after E. coli inoculation. Other animals (n=40) were administered IV TGF-beta1 or HSA at T0 and 6, 12 and 24 h after E. coli inoculation to investigate the effects of multiple treatments also on survival rates alone. All animals received ceftriaxone daily. Route of administration did not influence TGF-beta1 (p=ns for the effect of TGF-beta1 comparing IV vs IB routes) and we averaged over this variable in analysis. The relative risk of death (mean +/- sem) was not altered by either single treatments administered at T0 (-0.18 +/- 0.25, p=0.47) or multiple treatments (0.40 +/- 0.50, p=0.66) of TGF-beta1. Single treatment with TGF-beta1 first decreased and then increased vascular leukocytes at 6 and 168 h, respectively, but increased alveolar leukocytes at both time points (p=0.02 comparing the differing effects of TGF-beta1 on vascular and alveolar leukocytes at 6 and 168 h). Although TGF-beta1 decreased blood and lung bacteria counts at 6 and 168 h, it also increased serum tumor necrosis factor levels and lung injury scores at these time points (p<0.05 for the effects of TGF-beta1 on each parameter at 6 and 168 h together). Thus, while increases in lung leukocyte recruitment with TGF-beta1 were associated with improved microbial clearance in this rat model of pneumonia, worsened lung injury may have negated these beneficial host defense effects, and overall survival was not significantly improved. Despite these harmful effects, additional studies may be warranted to better define the influence of exogenous TGF-beta1 on host defense during acute bacterial infections.

Cytokines in periradicular lesions: the effect of linezolid treatment

OBJECTIVE

The purpose of this study was to quantify the cytokines interleukin (IL)-1 receptor antagonist (RA), IL-6, and transforming growth factor beta(1) found in extracts of inflammatory periapical tissues and to study the effect of a new antibiotic (linezolid) on the levels of these cytokines.

STUDY DESIGN

Twenty-two patients with root-filled teeth with persisting periapical pathoses were randomly divided into a control group or an antibiotic group. One tooth from each of the patients was resected at the root-end, and the periapical tissue was collected. IL-1RA, IL-6, and TGF-beta(1) were quantified in tissue extracts through the use of enzyme-linked immunosorbent assays.

RESULTS

Measurable amounts of all 3 cytokines were found in all extracts. A statistically significant reduction in IL-1RA per milliliter was observed in the linezolid group in comparison with the control group (P <.05). The difference in variation of IL-1RA in the treatment and control groups was also highly statistically significant (P <.001).

CONCLUSIONS

Although drawn from a limited sample size, the results indicate that IL-1RA is a sensitive indicator of the effect of antibacterial treatment on the immune response in periapical inflammatory tissues.

TGF-betas and their roles in the regulation of neuron survival

Transforming growth factor-betas (TGF-betas) are a still growing superfamily of cytokines with widespread distribution and diverse biological functions. They fall into several subfamilies including the TGF-betas 1, 2, and 3, the bone morphogenetic proteins (BMPs), the growth/differentiation factors (GDFs), activins and inhibins, and the members of the glial cell line-derived neurotrophic factor family. Following a brief description of their general roles and signaling in development, maintenance of homeostasis, and disease, we shall focus on their distribution in the CNS and their involvement in regulating neuron survival and death.

Analysis of the TGF-beta1 promoter polymorphism (C-509T) in patients with chronic periodontitis

BACKGROUND

A polymorphism in the promoter region of the transforming growth factor beta-1 (TGF-beta1) gene was described at position -509. This polymorphism represents a C-to-T base exchange, which creates a YY1 consensus sequence in an area involved with down transcription regulation. This polymorphism has been associated with risk for asthma and allergies. In this study we investigated the association between this polymorphism and chronic periodontitis severity.

METHODS

Genomic DNA from oral mucosa of 87 Caucasian subjects was amplified by PCR, and digested with Eco81I restriction endonuclease. The alleles were separated by polyacrylamide gel electrophoresis. The differences in genotype distribution from those expected by Hardy-Weinberg equilibrium, and the significance of the differences in observed frequencies of the polymorphism in moderate and severe disease and healthy groups were assessed by the chi2 test.

RESULTS

There was a difference in the presence of the different alleles and genotypes among the healthy, moderate and severe periodontitis groups. The allele T was seen at 57.7% in the group with severe periodontitis and 37.8% and 35.4% in the healthy group and moderate periodontitis group, respectively (p=0.0387). The genotype T/T was found at 38.5% in the group with severe periodontitis, and at a frequency of 8% in the healthy group (p=0.0258).

CONCLUSION

These results demonstrate that the polymorphism at bp -509 in the TGF-beta1 promoter may have a small effect on the modulation of the inflammatory process during periodontitis.

TGF-beta 1 suppresses [correction of supresses] myeloid Fc gamma receptor function by regulating the expression and function of the common gamma-subunit

We have previously reported that FcgammaR-mediated function in myeloid cells is a tightly regulated event that is influenced by the cytokines present in the milieu. TGF-beta1 is an immunosuppressive cytokine with pleiotropic effects on immune responses; however, the molecular mechanism by which TGF-beta suppresses immune responses is poorly understood. In this study, we have analyzed the effect of TGF-beta on FcgammaR-mediated activation of myeloid cells. We report that TGF-beta1-treated THP-1 human myeloid cells displayed reduced ability to phagocytose IgG-coated particles. Because FcgammaR expression is modulated by cytokines, we analyzed expression levels of FcgammaRI, FcgammaRIIa, FcgammaRIIb, and FcgammaRIIIa in cells cultured with or without TGF-beta1 and found while total protein levels of the FcgammaR were not reduced, surface expression of FcgammaRI and FcgammaRIII was lower in cells cultured with TGF-beta1. Concomitantly, there was a dose-dependent reduction in the expression of the FcgammaR-associated gamma-subunit. This suppressive effect of TGF-beta was likewise observed in bone marrow-derived murine myeloid cells and human monocytes. Importantly, TGF-beta1 also significantly reduced the production of monocyte chemoattractant protein-1 induced by immobilized IgG, which would further reduce monocyte recruitment to the site of inflammation. In contrast, human alveolar macrophages were refractory to this effect, expressing low levels of TGF-beta type II receptors compared with peripheral blood monocytes from the same donor. These data provide insight into the regulation of immune responses by TGF-beta1 and demonstrate the selectivity of these effects.

Transforming growth factor-beta: a mediator of cell regulation in acute respiratory distress syndrome

OBJECTIVE

To review recent advances in the use of transforming growth factor (TGF)-beta in acute lung injury and to apply this knowledge to understanding the pathophysiology of this syndrome.

DATA SOURCES AND STUDY SELECTION

Published research and review articles in the English language related to the role of TGF-beta in acute lung injury.

DATA EXTRACTION AND SYNTHESIS

The cytokine TGF-beta plays a critical role in the resolution of tissue injury in multiple organs, including the lung. Following injury, TGF-beta has been most thoroughly evaluated during the late phases of tissue repair, where it plays a critical role in the development of pulmonary fibrosis. In contrast, recent animal studies showed that expression levels of several TGF-beta-inducible genes were dramatically increased as early as 2 days after the induction of injury. The integrin alpha(v)beta(6) activates latent TGF-beta in the lungs. Mice lacking this integrin were completely protected from pulmonary edema in a model of bleomycin-induced acute lung injury. Pharmacologic inhibition of TGF-beta also protected wild-type mice from pulmonary edema induced by bleomycin or Escherichia coli endotoxin. Similar findings also have been reported in patients in a clinical study evaluating TGF-beta in the bronchoalveolar lavage fluid during the course of acute respiratory distress syndrome (ARDS). Indeed, the bronchoalveolar lavage concentrations were dramatically increased as early as 1 day after the initiation of ARDS criteria and were correlated with decreases in the Pao(2)/Fio(2) ratio, suggesting an important role for TGF-b1 in the development of ARDS in humans.

CONCLUSIONS

These studies suggest that TGF-beta not only participates in the late phase of acute lung injury, but also might be active early in acute lung injury and potentially could contribute to the development of pulmonary edema. Integrin-mediated local activation of TGF-beta is critical to the development of pulmonary edema in ARDS, and blocking TGF-beta or its activation could be an effective treatment for this disorder.

Expression of transforming growth factor-beta isoforms and their receptors in lepromatous and tuberculoid leprosy

Leprosy is an infectious disease with two polar forms, tuberculoid leprosy (TT) and lepromatous leprosy (LL), that are characterized by strong cell-mediated immunity (CMI) and CMI anergy, respectively. Transforming growth factor-beta (TGF-beta) belongs to a family of pleiotropic cytokines (TGF-beta1, TGF-beta2 and TGF-beta3) that participate in the control of cell differentiation and proliferation, as well as tissue repair. This cytokine family is unique because it suppresses CMI. In this study, we compared the expression of the three TGF-beta isoforms and their receptors in skin biopsies from LL and TT patients (LL = 20; TT = 20) using immunohistochemistry and automated morphometry. The percentage of cells immunostained for the three TGF-beta isoforms and cells positive for the three TGF-beta receptors in the inflammatory infiltrate located in the papillary dermis, reticular dermis and periadnexal tissue were significantly higher in LL than that in TT, with macrophages being the most common and strongest immunoreactive cells. Some lymphocytes, fibroblasts, keratinocytes and epithelial cells from sweat glands and hair roots were also positive. In situ reverse-transcription polymerase chain reaction corroborated the capacity of these cells to synthesize TGF-beta1 and TGF-beta receptor 2. This high expression of TGF-beta isoforms and their receptors could contribute to CMI anergy and other clinical characteristic features of leprosy, like skin atrophy.

Evidence for fibroblast growth factor receptors in myofibroblasts during palatal mucoperiosteal repair

Fibroblast growth factors (FGFs) regulate cell growth and differentiation and play crucial roles in the process of tissue repair and remodelling. We have previously shown that basic FGF is widely expressed at the injured site. Since the presence of FGF receptors (FGFRs) determines cellular responsiveness, we examined the localisation of FGFR1, FGFR2 and FGFR3 expression by immunohistochemistry throughout the repair of full-thickness excisional wounds up to 28 days after wounding. Strong expression of FGFR1 was observed in the nuclei of myofibroblasts, which are characterised by alpha-smooth muscle (alpha-SM) actin expression. The weak expression of FGFR2 was also observed in the nuclei of myofibroblasts. In contrast, there was no staining for FGFR3 in fibroblasts through the wound healing process. In addition, transforming growth factor-beta1 (TGF-beta1), a potential inducer of myofibroblasts, enhanced the expression of FGFR1 and FGFR2 in the nuclei of palatal fibroblasts in vitro. These findings suggest that FGFR1 and FGFR2 in myofibroblasts may be responsible for the signal transduction of FGF during the wound healing process.

Growth factors in the treatment of diabetic foot ulcers

BACKGROUND

Chronic foot ulceration is a major source of morbidity in diabetic patients. Despite traditional comprehensive wound management, including vascular reconstruction, there remains a cohort of patients with non-responding wounds, often resulting in amputation. These wounds may benefit from molecular manipulation of growth factors to enhance the microcirculation.

METHODS

A review of the current literature was performed using Pubmed, with secondary references obtained from key articles.

RESULTS AND CONCLUSION

There has been a generally disappointing clinical outcome from growth factor trials, although topical platelet-derived growth factor has shown significant benefit and should be considered in non-healing, well perfused ulcers after failure of conventional wound care. The modulatory role of the extracellular matrix in the cellular response to growth factors and data from regenerative-type fetal wound healing are further areas of interest. The chemical induction of microvessel formation may become a future therapeutic option.

Salivary gland expression of transforming growth factor beta isoforms in Sjogren's syndrome and benign lymphoepithelial lesions

AIM

Transforming growth factor beta (TGF-beta) is involved in the control of autoimmune reactions, cell proliferation, and the accumulation of lymphocytes within organs. The aim of this study was to determine the expression of TGF-beta in salivary glands from patients with primary Sjogren's syndrome (SS) and benign lymphoepithelial lesions (BLEL) with emphasis on ductal epithelium.

METHODS

Immunoperoxidase staining for TGF-beta isoforms and Ki67 antigen was performed on formalin fixed sections of labial glands from patients with primary SS (n = 15) and controls (n = 5) and parotid glands reported as BLEL (n = 5) or normal (n = 5). Ductal expression of TGF-beta was quantified by absorbance measurements using image analysis. The specificity of staining was confirmed by peptide blocking studies.

RESULTS

All TGF-beta isoforms were detected within the cytoplasm of most lymphocytes, endothelial cells, and ducts in all specimens. Acinar expression was variable and weaker than that seen in ducts. Absorbance measurements revealed that the expression of all isoforms was greater in ducts within primary SS glands than in control glands. Ductal expression in control parotid glands was greater than that seen in BLEL glands, irrespective of the presence of adjacent lymphoid infiltrates. Comparisons between control specimens showed that ductal expression of all isoforms was highest in parotid glands, whereas no differences were detected between primary SS and BLEL glands. Ki67 positive lymphocytes and duct cells were mainly restricted to pathological specimens, with BLEL glands containing larger populations of positive cells than primary SS glands.

CONCLUSION

These results demonstrate complex and variable changes in ductal expression of TGF-beta in primary SS and BLEL, which may be important in the control of lymphoid infiltration and the proliferation of lymphocytes and ductal epithelium.

The influence of platelet additive solutions on cytokine levels and complement activation in platelet concentrates during storage

BACKGROUND AND OBJECTIVES

The accumulation of platelet-derived cytokines in platelet concentrates (PC) during storage may contribute towards non-haemolytic transfusion reactions (NHTR). We investigated the effect of platelet storage medium on platelet activation, complement activation and cytokine levels in leucocyte-reduced PC.

MATERIALS AND METHODS

Hyperconcentrated platelets (3000-6000 x 109/l) were collected by apheresis and diluted in 100% plasma, 70% PASIII, or 70% or 80% PASIII supplemented with magnesium and potassium (PAS IIIM).

RESULTS

Levels of transforming growth factor-beta (TGF-beta) and regulated on activation, normal, T-cell expressed, and secreted (RANTES) increased during storage, as did the expression of P-selectin (CD62P), and were highest in PC stored in PASIII. In PC stored in PASIIIM, however, levels of TGF-beta and RANTES were not significantly different from PC stored in plasma. Levels of CD62P expression, however, remained higher in PASIIIM PC than in those stored in plasma by day 5, but were lower than PC stored in PASIII. C3a des arg levels increased during storage in all media with the exception of PASIII and, on day 7, were higher in PC stored in plasma compared to PC stored in the other media.

CONCLUSIONS

Our results indicate that replacing plasma in PC with unmodified PASIII for storage results in higher levels of platelet-derived cytokines in PC. Furthermore, it appears that the nature of the medium used for storage of PC has a significant impact on platelet activation and cytokine levels of the PC. These implications should be taken into account when considering replacement of plasma with PAS.

In vitro bioassay for transforming growth factor-beta using XTT method

Research in the cytokine field has grown exponentially in recent years, and the validity of such studies relies heavily on the appropriate measurement of levels of cytokines in various biological samples. Transforming growth factor (TGF)-beta, a hormonally active polypeptide found in normal and transformed tissue, is a potent regulator of cell growth and differentiation. The most widely used bioassay for TGF-beta is the inhibition of the proliferation of mink lung epithelial cells. Though detection of [3H]thymidine incorporation is more sensitive than the MTT assay, it presents some disadvantages due to the safety and disposal problems associated with radioisotopes. In this study, we attempted to ascertain the experimental conditions which could be used for measuring the in vitro biological activity of TGF-beta in a safer and more sensitive way compared with the currently available methods. We compared the commonly used method, the MTT assay, to the XTT assay using different parameters including cell number, incubation time and the wave length used for detecting the product. We examined the anti-proliferative activities of TGF-beta in three different cell lines: Mv-1-Lu mink lung epithelial cells, MCF10A human breast epithelial cells and H-ras-transformed MCF10A cells. Herein, we present an experimental protocol which provides the most sensitive method of quantifying the biological activity of TGF-beta, with a detection limit of as low as 10 pg/ml: Mv-1-Lu or H-ras MCF10 A cells (1 x 10(5)/well) were incubated with TGF-beta at 37 degrees C in a humidified CO2 incubator for 24 hr followed by XTT treatment and determination of absorbance at 450 or 490 nm. Our results may contribute to the establishment of an in vitro bioassay system, which could be used for the satisfactory quantitation of TGF-beta.

Molecular and functional dissection of TGF-beta1-induced cerebrovascular abnormalities in transgenic mice

Cerebrovascular abnormalities, such as reduced blood flow, microvascular fibrosis, and cerebrovascular amyloid angiopathy, are prominent in Alzheimer's disease (AD). However, their etiology is poorly understood and it is unclear whether cerebrovascular changes contribute to functional impairments in the absence of neurodegeneration. In humans with AD, transforming growth factor-beta1 (TGF-beta1) mRNA levels in the midfrontal gyrus correlate positively with the relative degree of cerebrovascular amyloid deposition in that brain region, suggesting a possible role for TGF-beta1 in human cerebrovascular abnormalities. Transgenic mice overexpressing TGF-beta1 in astrocytes develop AD-like cerebrovascular abnormalities, including perivascular astrocytosis, microvascular basement membrane thickening, and accumulation of thioflavin S-positive amyloid in the absence of parenchymal degeneration. Mice overexpressing TGF-beta1 alone or in addition to human amyloid precursor protein (hAPP) show selective accumulation of human beta-amyloid (Abeta) in blood vessels and develop cerebral hemorrhages in old age. In 9-month-old TGF-beta1 transgenic mice, cerebral blood flow (CBF) in the limbic system was significantly less than in nontransgenic littermate controls. Aged TGF-beta1 mice also showed overall reduced cerebral glucose uptake (CGU) as a measure of brain activity. Thus, chronic overproduction of TGF-beta1 in the brain results in structural and functional impairments reminiscent of those in AD cases with amyloid angiopathy.

Alcohol, injury, and cellular immunity

It is widely accepted that alcohol exposure is a causative factor in the occurrence of burn or other traumatic injury. It is less well known that individuals who have consumed alcohol before sustaining an injury suffer from increased morbidity and mortality compared with the morbidity and mortality of non-alcohol-consuming subjects with similar injuries. Complications due to bacterial infection are the most common burn sequelae in injured patients and are frequently associated with depressed immunity. Independently, alcohol exposure and injury have been shown to influence cellular immunity negatively. These changes in immunity are closely linked to injury- or alcohol-induced alterations in the cytokine milieu in both clinical studies and animal models. Not surprisingly, the combination of insult of alcohol exposure and burn injury results in immune suppression that is greater in magnitude and duration compared with either insult alone. The combined effects of alcohol and injury on immunity have been examined in a limited number of studies. However, results of these studies support the suggestion that altered cytokine production is an integral part of the immune dysregulation and increased mortality that is observed. In particular, the increased presence of macrophage-derived mediators observed after burn or alcohol exposure alone seems to be synergistically increased in a combined injury model. Although more research is needed, it is likely that therapeutic modalities that include manipulation of cytokine networks to boost cellular immunity may improve outcome for patients who sustain injuries subsequent to consuming alcohol.

Deficient transforming growth factor beta and interleukin-10 responses contribute to the septic death of burned patients

In order to understand the roles of pro-inflammatory and anti-inflammatory cytokines in burn injury and sepsis post-burn, serial changes in serum levels of transforming growth factor beta-1 (TGF-beta-1) were determined and compared to those of IL-6 and IL-10 in 15 burned patients. Among these 15 patients, 8 recovered without sepsis. The other seven, who were septic, expired. Our results showed that an initial peak serum TGF-beta-1 response was detected within 1 day post-burn. Peak serum IL-6 and IL-10 responses were also detected within 4 days after the burn injury of these patients. Significant differences in peak serum IL-6, IL-10 and TGF-beta-1 levels were not found between patients with total body surface area (TBSA) of greater or less than 50% and between patients who survived or expired from burn injury. Afterwards, levels of circulating IL-6 and IL-10 remained low in the survivors. However, a second peak response in serum TGF-beta-1 levels was observed in all burned patients analyzed. The second peak serum TGF-beta-1 levels post-burn of the eight survivors and the seven non-survivors were from 28,542 to 76,554 pg/ml (a mean value of 51,256+/-14,264 pg/ml) and from 8616 to 40,851 pg/ml (a mean value of 24,079+/-10,399 pg/ml), respectively. A significant difference (P<0.01) in mean values of the second peak TGF-beta-1 responses between groups of survivors and non-survivors was detected. Levels of circulating IL-6 in the septic non-surviving patients showed a tendency to increase 1-2 weeks post-burn and reached high levels before the expiration of these patients. After an initial peak response, the serum IL-10 level remained low in one of the seven non-survivors, while it increased in the other six non-survivors. However, marked increases in circulating IL-10 levels were observed only just before the death of these non-survivors. In conclusion, an initial increase in serum levels of IL-6, IL-10 and TGF-beta-1 was detected post-burn. A marked increase in serum levels of IL-6 before death suggests its role in the pathophysiology of sepsis in burned patients. In addition, a low secondary TGF-beta-1 response and a lack and/or delay in the increase of circulating IL-10 in the non-survivors may all contribute to the pathophysiology of septic death in burned patients.

Cytokine levels as performance indicators for white blood cell reduction of platelet concentrates

BACKGROUND AND OBJECTIVES

With the implementation of universal white blood cell (WBC) reduction in the UK, in-process WBC-reduction filters for pooled buffy coat (BC)-derived platelet concentrates (PCs) and apheresis methods are used routinely for the production of WBC-reduced PCs. While these strategies meet the specification for WBC reduction (< 5 x 10(6) WBCs/unit), the products from these processes may differ depending on the process employed and its performance. The aim of this study was therefore to investigate whether PCs prepared using various WBC-reduction processes are sufficiently depleted of WBCs to limit cytokine accumulation during storage and to assess if cytokine levels detected in platelet products can serve as indicators of acceptable platelet activation as a result of the WBC-reduction process.

MATERIALS AND METHODS

We measured the levels of cytokines predominantly derived from WBCs [e.g. interleukin-8 (IL-8)] and platelets [e.g. regulated on activation, normal, T-cell expressed, and secreted (RANTES) and transforming growth factor-beta(1) (TGF-beta(1))] under the present experimental conditions in different WBC-reduced PCs, i.e. PCs prepared from three different WBC-reduction filters and control non-filtered PCs using pooled BCs from the same donors and three apheresis types. Supernatant plasma was collected at the beginning (day 1) and end (day 5) of the shelf life of each PC, and the cytokine content was determined using appropriate enzyme-linked immunosorbent assays (ELISAs). Process efficiency was assessed by platelet yield and residual WBC count.

RESULTS

We found that products from the apheresis process involving a filtration step (Haemonetics MCS+) showed a lower cytokine content on both day 1 and day 5 in comparison with the fluidized bed (COBE Spectra) or elutriation (Amicus) processes. WBC reduction of BC-PCs of the same origin using three different filters showed comparable levels of cytokines on day 1 in all units. After storage for 5 days, the levels of IL-8 remained essentially unchanged in filtered BC-PCs but increased by more than threefold in control non-filtered BC-PCs, suggesting IL-8 release by residual WBCs present in the control PCs. The concentration of platelet-derived cytokines such as RANTES and TGF-beta(1), however, increased significantly in all filtered and control non-filtered PCs during the storage period.

CONCLUSION

These results show that markers of cytokine release from both WBCs and platelets are useful indicators of the performance and efficacy of the WBC-reduction process and of platelet quality.

Cytokine modulation in sepsis and septic shock

Sepsis and septic shock are a major cause of morbidity and mortality in patients admitted to the intensive care unit. Since the introduction of antibiotic therapy, the mortality associated with sepsis has remained within the 30- 50% range. Sepsis constitutes the systemic response to infection. This response encompasses both pro-inflammatory and anti-inflammatory phases that are marked by the sequential generation of pro- and anti-inflammatory cytokines. Among the most important pro-inflammatory cytokines are TNF-alpha and IL-1beta. The pro-inflammatory effects of such cytokines are inhibited by soluble receptors/receptor antagonists and anti-inflammatory cytokines including IL-10 and transforming growth factor-beta. Modulation of the activity of both pro- and anti-inflammatory cytokines to improve outcome in patients with sepsis has been subject of multiple clinical studies. This review will examine clinical trials evaluating several strategies for blocking or attenuating TNF-alpha and IL-1beta activity. This review will also survey the current state of experimental therapies involving IL-10, transforming growth factor-beta, granulocyte colony-stimulating factor and IFN-phi. Finally, newer developments related to less known cytokines such as macrophage migration inhibitory factor and high mobility group 1 protein will be evaluated.

Profiles of IFN-gamma and its regulatory cytokines (IL-12, IL-18 and IL-10) in peripheral blood mononuclear cells from patients with multidrug-resistant tuberculosis

This study investigated the profiles of IFN-gamma and its regulatory cytokines (IL-12, IL-18 and IL-10) in response to a purified protein derivative (PPD) antigen in peripheral blood mononuclear cells (PBMC) from 18 HIV-negative patients with multidrug-resistant tuberculosis (MDRTB), and compared them with those from 19 healthy tuberculin reactors (HTR). ELISA results showed that following stimulation with PPD, IFN-gamma production was significantly reduced, whereas production of both IL-18 and IL-10 was significantly elevated in MDRTB patients compared with HTR. Three out of 18 patients with MDRTB of greater than 4 years duration showed significantly elevated IL-12 p70 production, induced by in vitro PPD stimulation of their PBMC, when compared with data from HTR. However, when taken as a group, MDRTB patients were similar to HTR in their IL-12 p70-producing capacity. IL-12 p70 protein paralleled IL-12 p40 protein expression. In addition, the production of IL-12 p40 was significantly correlated with IL-10 in all patients, but was not correlated with IFN-gamma. Neutralization of IL-10 increased IL-12 p40 about twofold, but did not significantly alter IFN-gamma induction in MDRTB. IFN-gamma in MDRTB was highly correlated with lymphoproliferation and CD4 counts, but was not correlated with IL-12, IL-18 or IL-10 production. Our findings suggest that patients with MDRTB have dysregulated IL-12, IL-18 and IL-10 production during Mycobacterium tuberculosis infection, and the cytokine profiles are similar to those in patients with drug-sensitive advanced TB previously reported in the literature. In addition, IL-10 may not have a dominant role in defective IFN-gamma production in patients with MDRTB.

Transforming growth factor-beta expression in human retinal pigment epithelial cells is enhanced by Toxoplasma gondii: a possible role in the immunopathogenesis of retinochoroiditis

Retinochoroiditis caused by Toxoplasma gondii infection results in inflammation and necrosis of the retina. We have used human retinal pigment epithelial cultures (HRPE) as an in vitro model to investigate the role of TGF-beta in T. gondii-induced retinochoroiditis. RT-PCR analyses showed enhanced steady state levels of TGF-beta1 and TGF-beta2 mRNA in T. gondii-infected HRPE. Uninfected HRPE secrete TGF-beta1 in a latent form while 10-30% of the secreted TGF-beta2 was in the active form. T. gondii infection induced a significant increase (P < 0.01) in total TGF-beta1 and TGF-beta2 secretion by HRPE. In addition, soluble extracts of T. gondii (ST) stimulated secretion of both TGF-beta1 and TGF-beta2 significantly (P < 0.01). Interestingly, T. gondii infection as well as ST of the parasites completely inhibited secretion of the active form of TGF-beta2. Studies evaluating the effect of TGF-beta on T. gondii replication in HRPE revealed that TGF-beta enhanced parasite replication. The interactions between host retinal cells and T. gondii may play an active role in the pathogenesis of retinochoroiditis.

Macrophages influence a competition of contact guidance and chemotaxis for fibroblast alignment in a fibrin gel coculture assay

Rat dermal fibroblasts were dispersed initially in the outer shell of a fibrin gel sphere, while the inner core either was devoid of cells or contained peritoneal exudate cells (primarily macrophages), thereby mimicking the inflammatory phase of wound healing. The fibroblasts compacted floating fibrin microspheres over time. In the absence of macrophages, the initial distribution of fibroblasts (only in the shell) induced circumferential alignment of fibrin fibrils via compaction of the shell relative to the core. The aligned fibrils created a contact guidance field, which was manifested by strong circumferential alignment of the fibroblasts. However, in the presence of macrophages, the fibroblasts exhibited more radial alignment despite the simultaneous contact guidance field in the circumferential direction associated with compaction. This was attributed to a chemotactic gradient emanating from the core due to a putative factor(s) released by the macrophages. The presence of a radial chemotactic stimulus was supported by the finding of even greater radial alignment when fibrin microspheres were embedded in an agarose-fibrin gel that abolished compaction and consequently the contact guidance field. Our assay permits the simulation of tissue morphogenetic processes that involve cell guidance phenomena and tractional restructuring of the extracellular matrix.

Endocrine expression of the active form of TGF-beta1 in the TGF-beta1 null mice fails to ameliorate lethal phenotype

TGF-beta1 null mice die by 3 to 4 weeks of age due to a severe autoimmune-mediated multifocal inflammation resulting in multi-organ failure. To assess the therapeutic potential of circulating levels of active TGF-beta1, we generated mice with endocrine expression of active TGF-beta1 on a TGF-beta1 null background (TGF-beta1 (-/-/TG)) by crossing TGF-beta1(+/-) mice with transgenic mice (TG) that express recombinant TGF-beta1 specifically in the liver and secrete it in the blood. The TGF-beta1 (-/-/TG) mice exhibit a survival profile similar to the TGF-beta1 (-/-) mice indicating a failure to rescue the lethal phenotype. However, serum TGF-beta1 levels in the TGF-beta1 (-/-/TG) mice were restored to near normal levels with expression in all the tissues, notably in the kidney and spleen. Histopathology showed reduced inflammation in the target tissues, especially in the heart. Interestingly, unlike TGF-beta1 (-/-) mice, the TGF-beta1 (-/-/TG) mice have glomerulonephritis in their kidneys similar to the TG mice. Thus, the phenotype of TGF-beta1 (-/-/TG) animal model indicates the potential role of circulating active-TGF-beta1 in reducing inflammation, but its failure to rescue lethality in TGF-beta1 null mice indicates a critical autocrine role of TGF-beta1.

TGF-beta and the regulation of neuron survival and death

Transforming growth factor-betas (TGF-betas) constitute a superfamily of multifunctional cytokines with important implications in morphogenesis, cell differentiation, and tissue remodeling. In the developing nervous system, TGF-beta2 and -beta3 occur in radial and astroglial cells as well as in many populations of postmitotic, differentiating neurons. TGF-beta1 is restricted to the choroid plexus and meninges. In addition to functions related to glial cell maturation and performances, TGF-beta2 and -beta3 are important regulators of neuron survival. In contrast to neurotrophic factors, as for example, neurotrophins, TGF-betas are most likely not neurotrophic by themselves. However, they can dramatically increase the potency of select neurotrophins, fibroblast growth factor-2, ciliary neurotrophic factor, and glial cell line-derived neurotrophic factor (GDNF). In the case of GDNF, we have shown that GDNF fails to promote the survival of highly purified neuron populations in vitro unless it is supplemented with TGF-beta. This also applies to the in vivo situation, where antibodies to all three TGF-beta isoforms fully prevent the trophic effect of GDNF on axotomized, target-deprived neurons. In addition to the TGF-beta isoforms -beta2 and -beta3, other members of the TGF-beta superfamily are expressed in the nervous system having important roles in embryonic patterning, cell migration, and neuronal transmitter determination. We have cloned and expressed a novel TGF-beta, named growth/differentiation factor-15 (GDF-15). GDF-15 is synthesized in the choroid plexus and released into the CSF, but also occurs in all regions investigated of the developing and adult brain. GDF-15 is a potent trophic factor for developing and 6-OHDA-lesioned midbrain dopaminergic neurons in vitro and in vivo, matching the potency of GDNF.

Curcumin differentially regulates TGF-beta1, its receptors and nitric oxide synthase during impaired wound healing

Wound healing is a highly ordered process, requiring complex and coordinated interactions involving peptide growth factors of which transforming growth factor-beta (TGF-beta) is one of the most important. Nitric oxide is also an important factor in healing and its production is regulated by inducible nitric oxide synthase (iNOS). We have earlier shown that curcumin (diferuloylmethane), a natural product obtained from the plant Curcuma longa, enhances cutaneous wound healing in normal and diabetic rats. In this study, we have investigated the effect of curcumin treatment by topical application in dexamethasone-impaired cutaneous healing in a full thickness punch wound model in rats. We assessed healing in terms of histology, morphometry, and collagenization on the fourth and seventh days post-wounding and analyzed the regulation of TGF-beta1, its receptors type I (tIrc) and type II (tIIrc) and iNOS. Curcumin significantly accelerated healing of wounds with or without dexamethasone treatment as revealed by a reduction in the wound width and gap length compared to controls. Curcumin treatment resulted in the enhanced expression of TGF-beta1 and TGF-beta tIIrc in both normal and impaired healing wounds as revealed by immunohistochemistry. Macrophages in the wound bed showed an enhanced expression of TGF-beta1 mRNA in curcumin treated wounds as evidenced by in situ hybridization. However, enhanced expression of TGF-beta tIrc by curcumin treatment observed only in dexamethasone-impaired wounds at the 7th day post-wounding. iNOS levels were increased following curcumin treatment in unimpaired wounds, but not so in the dexamethasone-impaired wounds. The study indicates an enhancement in dexamethasone impaired wound repair by topical curcumin and its differential regulatory effect on TGF-beta1, it's receptors and iNOS in this cutaneous wound-healing model.

Response to hypoxia involves transforming growth factor-beta2 and Smad proteins in human endothelial cells

Oxygen deprivation (hypoxia) is a consistent component of ischemia that induces an inflammatory and prothrombotic response in the endothelium. In this report, it is demonstrated that exposure of endothelial cells to hypoxia (1% O(2)) increases messenger RNA and protein levels of transforming growth factor-beta2 (TGF-beta2), a cytokine with potent regulatory effects on vascular inflammatory responses. Messenger RNA levels of the TGF-beta2 type II membrane receptor, which is a serine threonine kinase, also increased. The stimulatory effect of hypoxia was found to occur at the level of transcription of the TGF-beta2 gene and involves Smad proteins, a class of intracellular signaling proteins that mediates the downstream effects of TGF-beta receptors. Transient transfection studies showed that the region spanning -77 and -40 base pairs within the TGF-beta2 promoter (harboring a Smad-binding "CAGA box") is activated in hypoxic cells compared with nonhypoxic controls (P <.01). Hypoxia also stimulated transcription from another promoter, 3TP-Lux, a reporter construct responsive to Smads and TGF-beta. In addition, specific binding to a Smad-binding oligonucleotide was observed with nuclear extracts from hypoxic endothelial cells but not from nonhypoxic cells. It is concluded that Smad proteins, which can regulate endothelial responses to mechanical and inflammatory stress, also may play an important role in vascular responses to hypoxia and ischemia.

Peptide growth factors in the intestine

A continuously increasing number of regulatory peptides has been demonstrated to be expressed in the intestine and to modulate several functional properties of various intestinal cell populations, including the intestinal epithelium and lamina propria cell populations. These regulatory peptides include members of the epidermal growth factor (EGF) family, the transforming growth factor beta (TGF-beta) family, the insulin-like growth factor (IGF) family, the fibroblast growth factor (FGF) family, the trefoil factor (TFF) family, the colony-stimulating factor (CSF) family, and a few other seemingly unrelated regulatory peptides, such as hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF), and various interleukins, interferons and tumour necrosis factor-related proteins. In addition to the well-known effects on cell proliferation, these regulatory peptide factors regulate several other functional properties of epithelial and other cell populations, such as differentiation, migration, and extracellular matrix deposition and degradation. This review is designed not to discuss all the identified factors in detail but to highlight some of the basic principles of growth factor action in the intestine. It focuses mainly on classical growth factors rather than interleukins and interferons.

Mast cells in acute and chronic rejection of rat cardiac allografts--a major source of basic fibroblast growth factor

BACKGROUND

Studies of cardiac allograft arteriosclerosis, i.e., chronic rejection, have largely focused on mononuclear inflammatory cell infiltrates in the vascular wall and periphery of the occluded vessels. The purpose of this study was to investigate the role of mast cells in the development of acute and chronic rejection in rat cardiac allografts.

METHODS

In the acute rejection model, transplant recipients were not treated with immunosuppressants, and the grafts were removed 5 days after transplantation at the time of severe acute rejection. In the chronic rejection model, the recipients were administered triple-drug immunosuppression, and the grafts were removed 90 days after transplantation.

RESULTS

During acute rejection, the number of mast cells was not increased, but the localization pattern differed from that of syngeneic grafts. In acute rejection, mast cells were located in the perivascular region of the allografts, but in syngeneic grafts, mast cells had a more interstitial location. In the chronic rejection model, the cardiac allografts with severe intimal thickening showed large numbers of mast cells at perivascular sites of occluded intramyocardial vessels and in the interstitium. Linear regression analysis revealed a significant correlation between the numbers of perivascular and interstitial mast cells and the intensity of intimal thickening. The majority of mast cells showed positive immunoreactivity to basic fibroblast growth factor (bFGF). Macrophage bFGF expression was not so prominent, but macrophages were more frequent in numbers. Tumor necrosis factor-alpha expression was detected mainly in macrophages and in only a few mast cells. When the intensity of arteriosclerosis was decreased by an increase in the intensity of immunosuppression, the numbers of intragraft mast cells and other mononuclear cells, and also the production of their respective cytokines, bFGF and tumor necrosis factor-alpha, gradually diminished.

CONCLUSIONS

Taken together, our data show that the intensity of intramyocardial mast cell infiltration was associated with the intensity of chronic inflammation and allograft arteriosclerotic changes, but not with acute rejection, and that mast cells, in addition to macrophages, are a major source of myocardial bFGF. The results also demonstrate that when the T-cell activation pathway is blocked using cyclosporin, the number of mast cells is decreased. Cyclosporin may have affected the cytokine production that interfered with both the mast cell-dependent initiation and the leukocyte- and mast cell-dependent amplification and progression of the immune responses influenced by mast cell-leukocyte cytokine cascades. bFGF produced by mast cells may contribute to enhanced inflammation, neovascularization, and fibrosis during cardiac allograft arteriosclerosis.

Identification of soluble transforming growth factor-beta receptor III (sTbetaIII) in rat milk

Transforming growth factor-beta (TGF-beta) is present at high concentrations in maternal milk. In milk TGF-beta2 is the predominant isoform. For function TGF-beta2 requires TbetaRIII to facilitate efficient binding to the TGF-beta receptor types I and II signalling complex. We have shown that TGF-beta receptor types I (TbetaRI), II (TbetaRII) and III (TbetaRIII) are coexpressed in the suckling rat intestine. Immunostaining for TbetaRIII was also observed in the intestinal lumen prior to weaning. TbetaRIII (or betaglycan) has been reported in serum, cell culture medium and extracellular matrix. To determine whether a soluble form of TbetaRIII is present in milk, the rat milk aqueous phase was analysed by slot-blot and Western blot. Soluble TbetaRIII was detected in milk throughout lactation. Western blot analysis of rat milk revealed a high molecular weight band of glycosylated protein of >200 kDa, with a core protein of approximately 110-120 kDa that comigrated with recombinant TbetaRIII. Immunoabsorption of soluble TbetaRIII (sTbetaRIII) from milk resulted in partial depletion of active TGF-beta from milk, suggesting that the receptor may interact with ligand in milk. In addition rat pups suckled on mother's milk demonstrated an enhanced labelling of TbetaRIII in the gut, as compared with pups fed on a rat milk substitute (RMS). These findings suggest that milk sTbetaRIII is functional, and may modulate milk-derived TGF-beta function in the developing intestine.

Antigen recognition and immunomodulation by gamma delta T cells in bovine tuberculosis

This report describes the in vitro proliferative responses of peripheral blood gammadelta T cells to defined mycobacterial protein Ags and the immunomodulatory effect of gammadelta T cells in cattle infected with Mycobacterium bovis. gammadelta T cell responses were specific to M. bovis infection because they were detected in cattle either experimentally or naturally infected with M. bovis, but were not present in uninfected controls. Proliferating gammadelta T cell cultures produced enhanced levels of IFN-gamma and TGF-beta, but not IL-2 in response to the more immunodominant mycobacterial AGS: Depletion of gammadelta T cells from PBMC resulted in an increased Ag-specific proliferation in half the animals tested, indicating a suppressive effect of gammadelta T cells upon other (alphabeta) T cell responses. Because gammadelta T cells constitute a major T cell population in the peripheral blood of cattle, the activities of gammadelta T cells described in this report could make a significant contribution to the immune response in bovine tuberculosis.

TGF-beta1 promotes microglial amyloid-beta clearance and reduces plaque burden in transgenic mice

Abnormal accumulation of the amyloid-beta peptide (Abeta) in the brain appears crucial to pathogenesis in all forms of Alzheimer disease (AD), but the underlying mechanisms in the sporadic forms of AD remain unknown. Transforming growth factor beta1 (TGF-beta1), a key regulator of the brain's responses to injury and inflammation, has been implicated in Abeta deposition in vivo. Here we demonstrate that a modest increase in astroglial TGF-beta1 production in aged transgenic mice expressing the human beta-amyloid precursor protein (hAPP) results in a three-fold reduction in the number of parenchymal amyloid plaques, a 50% reduction in the overall Abeta load in the hippocampus and neocortex, and a decrease in the number of dystrophic neurites. In mice expressing hAPP and TGF-beta1, Abeta accumulated substantially in cerebral blood vessels, but not in parenchymal plaques. In human cases of AD, Abeta immunoreactivity associated with parenchymal plaques was inversely correlated with Abeta in blood vessels and cortical TGF-beta1 mRNA levels. The reduction of parenchymal plaques in hAPP/TGF-beta1 mice was associated with a strong activation of microglia and an increase in inflammatory mediators. Recombinant TGF-beta1 stimulated Abeta clearance in microglial cell cultures. These results demonstrate that TGF-beta1 is an important modifier of amyloid deposition in vivo and indicate that TGF-beta1 might promote microglial processes that inhibit the accumulation of Abeta in the brain parenchyma.

Elevated iron status increases bacterial invasion and survival and alters cytokine/chemokine mRNA expression in Caco-2 human intestinal cells

Iron status affects both microbial growth and immune function. Mammalian iron homeostasis is maintained primarily by regulating the absorption of the micronutrient in the proximal small intestine. The iron concentration of the enterocyte can fluctuate widely in response to both dietary and whole body iron status, as well as in response to infections. The possibility that an enterocyte with an elevated iron concentration is more susceptible to invasion by enteric pathogens is not known. Therefore, we examined the impact of enterocyte iron status on the invasion and survival of an enteric pathogen, as well as on the levels of several cytokine and chemokine mRNAs by the host cell. The enterocyte-like Caco-2 human intestinal cell line and Salmonella enteritidis served as the models to examine the effect of iron on the host-parasite interaction. Iron status of Caco-2 cells was altered by incubation in serum-free medium supplemented with varying levels of iron. Elevated iron status of Caco-2 cells increased the efficiency of the invasion and the number of bacteria surviving in the intracellular environment. Caco-2 cells constitutively expressed transforming growth factor-beta1, interleukin-8, monocyte chemotactic protein-1, tumor necrosis factor-alpha and interleukin-1beta, and infection with S. enteritidis increased the relative quantities of all cytokine/chemokine mRNAs except interleukin-1beta. Elevated iron status of Caco-2 cells decreased the levels of cytokine/chemokine mRNAs by 25-45% in uninfected cells. In contrast, bacterial infection was associated with a 21-95% increase in cytokine/chemokine mRNAs levels in Caco-2 cells with higher iron concentration compared with infected cells with lower iron concentration. These data support the hypothesis that elevated enterocyte iron status increases susceptibility to infection and exacerbates the mucosal inflammatory response initiated by microbial invasion by increasing cytokine/chemokine expression.

GDF-15/MIC-1 a novel member of the TGF-beta superfamily

We have cloned, expressed, and raised antibodies against a novel member of the TGF-beta superfamily, growth/differentiation factor-15 (GDF-15). The predicted protein is identical to macrophage inhibitory cytokine-1 (MIC-1), which was discovered simultaneously. GDF-15 is a more distant member of the TGF-beta superfamily and does not belong to one of the known TGF-beta subfamilies. In the CNS, GDF-15/MIC-1 mRNA is abundantly expressed by the choroid plexus. In addition we have preliminary evidence that GDF-15/MIC-1 is a potent trophic factor for selected classes of neurons in vitro and in vivo. Thus, GDF-15 is a novel neurotrophic factor with prospects for the treatment of disorders of the CNS.

Is TGF-beta1 the key to suppression of human asthma?

Transforming growth factor beta1 (TGF-beta1) is produced by many types of cells that are activated in the asthmatic response. Recent studies have highlighted this cytokine as an important negative regulator in an experimental model of asthma. Although the role of TGF-beta1 in human asthma remains obscure, data derived from animal models have encouraged the further investigation of such suppression mechanisms in order to develop novel therapies for asthma.

Transforming growth factor-beta increases the expression of aminopeptidase N/CD13 mRNA and protein in monocytes and monocytic cell lines

Aminopeptidase N (APN)/CD13 is a membrane-bound surface ectopeptidase with a ubiquitous distribution. In hematopoiesis, APN/CD13 is expressed on stem cells and during most developmental stages of myeloid cells. Because APN/CD13 has been implicated in the trimming on the cell surface of peptides that protrude out of MHC class II molecules, we wanted to study the regulation of this membrane peptidase in antigen presenting cells by TGF-beta. TGF-beta is a potent inducer of the maturation of monocyte precursors towards a macrophage phenotype. Using competitive RT-PCR and cytofluorimetric analyses, we quantified the modulation of the APN/CD13 mRNA as well as protein expression by TGF-beta 1 and -2 and found a stimulation of the APN/CD13 expression in a time- and dose-dependent manner in monocytic cells. In U937 cells, the time course showed a maximum for APN/CD13 mRNA at 24 hours incubation with TGF-beta. In experiments with actinomycin D- treated cells was found a stabilization of APN/CD13 mRNA by TGF-beta 1. Contrary to the IL-4-induced expression of APN/CD13 as well as of MHC class II in monocytic cells, we could show that TGF-beta is able to augment the APN/CD13 expression but decreases the MHC class II expression.

Mechanisms and modulation of intestinal epithelial repair

The mucosal epithelium of the alimentary tract represents a crucial barrier to a broad spectrum of noxious and immunogenic substances within the intestinal lumen. An impairment of the integrity of the mucosal epithelial barrier is observed in the course of various intestinal disorders including inflammatory bowel diseases (IBD), celiac disease, intestinal infections, and various other diseases. Furthermore, even under physiologic conditions temporary damage of the epithelial surface mucosa may be caused by proteases, residential flora, dietary compounds, or other factors. Generally, the integrity of the intestinal mucosal surface barrier is rapidly reestablished even after extensive destruction because of an enormous regenerative capability of the mucosal surface epithelium. Rapid resealing of the surface epithelium is accomplished by epithelial cell migration, also termed epithelial restitution, epithelial cell proliferation, and differentiation. Healing of the intestinal surface epithelium is regulated by a complex network of highly divergent factors, among them a broad spectrum of structurally distinct regulatory peptides that have been identified within the mucosa of the intestinal tract. These regulatory peptides, conventionally designated as growth factors and cytokines, play an essential role in regulating differential epithelial cell functions to preserve normal homeostasis and integrity of the intestinal mucosa. In addition, a number of other peptide molecules such as extracellular matrix factors and blood clotting factors, and also nonpeptide molecules including phospholipids, shortchain fatty acids, adenine nucleotides, trace elements, and pharmacological agents, have been demonstrated to modulate intestinal epithelial repair mechanisms. Some of these molecules may be released by platelets, adjacent stromal cells, inflammatory cells, or injured epithelial and nonepithelial cells and may play an important role in the modulation of intestinal injury. Repeated damage and injury of the intestinal surface are key features of various intestinal disorders including IBD and require constant repair of the epithelium. Enhancement of intestinal repair mechanisms by regulatory peptides or other modulatory factors may provide future approaches for the treatment of diseases that are characterized by injuries of the epithelial surface.

Evidence that furin is an authentic transforming growth factor-beta1-converting enzyme

Transforming growth factor (TGF)-beta1 plays an essential role in cell growth and differentiation. It is also considered as a gatekeeper of immune homeostasis with gene disruption leading to autoimmune and inflammatory diseases. TGF-beta1 is produced as an inactive precursor polypeptide that can be efficiently secreted but correct proteolytic cleavage is an essential step for its activation. Assessment of the cleavage site has revealed a unique R-H-R-R sequence reminiscent of proprotein convertase (PC) recognition motifs and has previously demonstrated that this PC-like cleavage site is correctly cleaved by furin, a member of the PC family. Here we report that among PC members, furin more closely satisfies the requirements needed to fulfill the role of a genuine TGF-beta1 convertase. Even though six members of the PC family have the ability to cleave TGF-beta1, ectopic expression of alpha(1)-antitrypsin Portland (alpha(1)-AT-PDX), a potent furin inhibitor, blocked 80% of TGF-beta1 processing mediated by endogenous enzymes as demonstrated in an in vitro digestion assay. Genetic complementation of a furin-deficient LoVo cell line with the wild-type gene restores the production of mature and bioactivable TGF-beta1. Moreover, both furin and TGF-beta are coordinately expressed and regulated in vitro and in vivo in the hematopoietic and immune system, an important tissue target. These results demonstrate for the first time that furin is an authentic and adaptive TGF-beta1-converting enzyme whereas other members of the PC family might substitute or supplement furin activity. Our study advances our comprehension of the complexity of the TGF-beta system and should facilitate the development of therapeutically useful TGF-beta inhibitors.

The role of up-regulated serine proteases and matrix metalloproteinases in the pathogenesis of a murine model of colitis

Proteinases are important at several phases of physiological and pathological inflammation, mediating cellular infiltration, cytokine activation, tissue damage, remodeling, and repair. However, little is known of their role in the pathogenesis of inflammatory bowel disease. The aim of this study was to assess the role of tissue proteases in a mouse model of colitis. Proteolytic activity was analyzed, using gel and in situ zymography, in colonic tissues from severe combined immunodeficient mice with colitis induced by transfer of CD4(+) T lymphocytes. Serine proteinase levels increased in colitic tissue, with major species of 23 kd, 30 kd, and 45 kd. Co-migration and inhibition studies indicated that the 23-kd proteinase was pancreatic trypsin and that the 30-kd species was neutrophil elastase. Matrix metalloproteinase (MMP)-9 expression, and MMP-2 and MMP-9 activation, was elevated in colitic tissues. Proteinase levels followed a decreasing concentration gradient from proximal to distal colon. Proteolysis was localized to infiltrating leukocytes in diseased severe combined immunodeficient mice. Transmural inflammation was associated with serine proteinase and MMP activity in overlying epithelium and with marked subepithelial proteolytic activity. The results demonstrate a clear elevation in the levels and activation of proteases in colitis, potentially contributing to disease progression through loss of epithelial barrier function.

Roles of tumour necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), and IL-10 in the modulation of intercellular adhesion molecule-1 (ICAM-1) expression by macrophages during mycobacterial infection

Profiles of ICAM-1 expression on cultured murine peritoneal macrophages infected with Mycobacterium avium complex (MAC) were examined, with special reference to modulating roles of TNF-alpha, TGF-beta, and IL-10. When macrophages were infected with MAC, ICAM-1 expression, measured by microscopic counting of ICAM-1+ macrophages stained with anti-ICAM-1 antibody, ELISA, and flow cytometric analysis, was rapidly increased, peaking at day 3 (early-phase up-regulation) due to endogenous TNF-alpha, and thereafter gradually declined to the normal level within 1 week or more (late-phase down-regulation). The late-phase ICAM-1 down-regulation was also seen in macrophages phagocytosing heat-killed MAC and those stimulated with lipopolysaccharide but not in macrophages phagocytosing latex beads. ICAM-1 mRNA expression was augmented markedly at day 1 after MAC infection and thereafter decreased. While TNF-alpha and IL-10 production by MAC-infected macrophages was observed during the first 3 days, TGF-beta production was initiated from day 3 and continued until day 14. Exogenously added TGF-beta strongly inhibited the early-phase increase in ICAM-1 expression by infected macrophages, and the blockade of endogenous TGF-beta with anti-TGF-beta antibody markedly inhibited late-phase ICAM-1 down-regulation. Moderate blocking effect was also observed for anti-IL-10 antibody. On the other hand, late-phase ICAM-1 down-regulation was not prevented by the addition of exogenous TNF-alpha. Therefore, TGF-beta and IL-10, especially the former, appear to play active roles in the late-phase down-regulation of ICAM-1 in MAC-infected macrophages during long-term cultivation.

In situ expression of transforming growth factor-beta1-3, latent transforming growth factor-beta binding protein and tumor necrosis factor-alpha in liver tissue from patients with chronic hepatitis C

BACKGROUND

The mechanisms determining liver damage in chronic hepatitis C remain unclear. The aim was to evaluate the in situ expression of transforming growth factor beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha), two key cytokines implicated as important pathogenic mediators in the development of liver fibrosis.

METHODS

In situ expression of TNF-alpha and of TGF-beta isoforms 1-3, and its transport protein latent TGF-beta binding protein (LTBP), was determined by immunohistochemistry in 9 untreated patients with chronic hepatitis C infection and in 6 controls without liver disease. In addition, TGF-beta1 expression was analyzed in 10 HCV patients before and after treatment with interferon-alpha alone, or in combination with ribavirin.

RESULTS

Liver biopsies from HCV patients showed positive staining for TGF-beta1-3 isoforms and LTBP, and to a lesser degree for TNF-alpha, in areas with inflammation and fibrosis. Normal control liver showed no positive staining. TGF-beta1 expression before treatment, quantified by morphometric analysis, did not differ between non-responders and sustained responders. In patients responding to therapy, TGF-beta1 expression decreased in parallel with histological improvement, while no difference in TGF-beta1 expression was seen before and after treatment in non-responders.

CONCLUSION

These results suggest that TNF-alpha and all three isoforms of TGF-beta are involved in the pathogenesis of HCV related liver disease, and that treatment leading to eradication of the virus affects the expression of TGF-beta1.

The transforming growth factor-betas: structure, signaling, and roles in nervous system development and functions

Transforming growth factor-betas (TGF-betas) are among the most widespread and versatile cytokines. Here, we first provide a brief overview of their molecular biology, biochemistry, and signaling. We then review distribution and functions of the three mammalian TGF-beta isoforms, beta1, beta2, and beta3, and their receptors in the developing and adult nervous system. Roles of TGF-betas in the regulation of radial glia, astroglia, oligodendroglia, and microglia are addressed. Finally, we review the current state of knowledge concerning the roles of TGF-betas in controlling neuronal performances, including the regulation of proliferation of neuronal precursors, survival/death decisions, and neuronal differentiation.

[Radiation-induced superficial fibrosis and TGF-alpha 1]

Radiation-induced fibrosis is a late sequela of both therapeutic and accidental irradiations, which has been described in various tissues, including the lung, liver, kidney and skin. This review presents different aspects of superficial radiation-induced fibrosis, such as clinical observations, histological changes, cellular and molecular regulations, and medical management. Recent evidence on the critical role played by TGF-beta 1 in the initiation, development and persistence of fibrosis are discussed, as well as the possibility that this cytokine may constitute a specific target for antifibrotic agents.