Hyperthermia induces expression of transforming growth factor-beta s in rat cardiac cells in vitro and in vivo

Thermotolerance and plasticity of camel somatic cells exposed to acute and chronic heat stress

The Arabian camel is the largest known mammal that can survive in severe hot climatic conditions. We provide the molecular explanation for the thermotolerance of camel granulosa somatic cells after exposure to 45 °C for 2 (acute heat shock) or 20 h (chronic heat shock). The common features of the cellular responses to acute heat stress were the increase of heat shock proteins and DNA repair enzymes expression. Actin polymerization and Rho signaling were critically activated as a cellular defense against heat shock. Cells exposed to chronic heat shock showed altered cell architecture with a decrease in total detected proteins, metabolic enzymes, and cytoskeletal protein expression. Treatment with transforming growth factor beta (TGFβ) pathway inhibitor SB-431542 suppressed the morphological alterations of cells exposed to chronic heat shock. Moreover, during the recovery stage at 38 °C for 24 h, proteomic changes were partially restored with an exponential increase in HSP70 expression, and the cells restored their normal cellular morphology on the 9th day of recovery. Full proteomics data are available via ProteomeXchange with identifier PXD012159. The strategies of cellular defense and tolerance to both thermal conditions reflect the flexible adaptability of camel somatic cells to conserve life under extremely hot conditions.

MicroRNA-34a regulates cardiac fibrosis after myocardial infarction by targeting Smad4

BACKGROUND

Although few microRNAs (miRNAs) have been involved in the regulation of post-ischemic cardiac fibrosis, the exact effect and underlying mechanism of miRNAs in cardiac fibrosis remains unclear. Here, we sought to investigate whether microRNA-34 (miR-34) plays a role in the pathogenic development of myocardial fibrosis.

METHODS

The myocardial infarction (MI) mice model was induced and cardiac fibroblasts were cultured. Histological analyses, quantitative real-time polymerase chain reaction and Western blotting analysis were used.

RESULTS

We found that the miR-34 cluster, especially miR-34a, was upregulated in the MI heart. In vivo, inhibition of miR-34a reduces the severity of experimental cardiac fibrosis in mice. TGF-β1 increased miR-34a expression in cardiac fibroblasts. Overexpressing miR-34a levels increased the profibrogenic activity of TGF-β1 in cardiac fibroblast, whereas inhibition miR-34a levels weakened the activity. Finally, we showed that miR-34a's underlying mechanism during cardiac fibrosis occurs through the targeting of Smad4 expression.

CONCLUSIONS

Our findings provide evidence that miR-34a plays a critical role in the progression of cardiac tissue fibrosis by directly targeting Smad4, which suggests that miR-34a may be new marker for cardiac fibrosis progression and that inhibition of miR-34a may be a promising strategy in the treatment of cardiac fibrosis.

Proteome profiling of heat shock of human primary breast epithelial cells, a dataset report

Exposure to elevated temperatures has a strong effect on cell functions, and is used in clinical practice. Hyperthermia may affect multiple regulatory mechanisms in cells. To understand better the response to hyperthermia of immortalized primary human breast epithelial cells, we performed a proteomics study of these cells cultured at 34°C or 39°C. Twenty-four proteins were shown to be differentially expressed due to hyperthermia. Analysis of these proteins showed the potential involvement of various biological processes in response to hyperthermia, e.g., cell adhesion, cell communication, and cell cycle. Transforming growth factor-β2 (TGF-β2) and heat shock protein 27 (HSP27) were found to be upregulated at 39°C. TGF-β2 was found to affect expression of HSP27, and to have a protective role in hyperthermia-induced cell death. Thus, the dataset described here of hyperthermia-related proteins in human primary breast epithelial cells predicts a number of cellular activities affected by exposure to high temperatures and provides a set of proteins for further studies.

Immunohistochemical investigation of wound healing in response to fractional photothermolysis

Despite growing clinical evidence of ablative fractional photothermolysis (AFP), little is known about the spatiotemporal molecular changes within the targeted compartments. Six subjects received three different single AFP treatments using a scanned 250 mum CO(2)-laser beam. Spatiotemporal changes of skin regeneration were estimated by immunohistochemical investigation (HSP70, HSP72, HSP47, TGFbeta, procollagen III, CD3, CD20, and CD68) in skin samples 1 h, 3 days, and 14 days postintervention. The remodeling was uniformly started by regrowth of the epidermal compartment followed by partial to complete replacement of the microscopic ablation zones (MAZ) by newly synthesized condensed procollagen III. From day 3 to 14, the number of macrophages as well as giant cells surrounding the MAZ increased. TGFbeta expression was highest 1 h to 3 days following AFP. HSP70 and HSP72 expressions were highest 3-14 days postintervention in the spinocellular layer leading to an upregulation of HSP47. AFP performed by a scanned CO(2)-laser results in an early epidermal remodeling, which is followed by a dermal remodeling leading to a replacement of the MAZ with newly synthesized (pro)-collagen. During this, an inflammatory infiltrate with CD3(+) and CD20(+) cells surrounds the MAZ. The count of macrophages and giant cells involved in the replacement of the necrotic zones seems to be crucial for wound healing.

Downregulation of miR-133 and miR-590 contributes to nicotine-induced atrial remodelling in canines

AIMS

The present study was designed to decipher molecular mechanisms underlying nicotine's promoting atrial fibrillation (AF) by inducing atrial structural remodelling.

METHODS AND RESULTS

The canine model of AF was successfully established by nicotine administration and rapid pacing. The atrial fibroblasts isolated from healthy dogs were treated with nicotine. The role of microRNAs (miRNAs) on the expression and regulation of transforming growth factor-beta1 (TGF-beta1), TGF-beta receptor type II (TGF-betaRII), and collagen production was evaluated in vivo and in vitro. Administration of nicotine for 30 days increased AF vulnerability by approximately eight- to 15-fold in dogs. Nicotine stimulated remarkable collagen production and atrial fibrosis both in vitro in cultured canine atrial fibroblasts and in vivo in atrial tissues. Nicotine produced significant upregulation of expression of TGF-beta1 and TGF-betaRII at the protein level, and a 60-70% decrease in the levels of miRNAs miR-133 and miR-590. This downregulation of miR-133 and miR-590 partly accounts for the upregulation of TGF-beta1 and TGF-betaRII, because our data established TGF-beta1 and TGF-betaRII as targets for miR-133 and miR-590 repression. Transfection of miR-133 or miR-590 into cultured atrial fibroblasts decreased TGF-beta1 and TGF-betaRII levels and collagen content. These effects were abolished by the antisense oligonucleotides against miR-133 or miR-590. The effects of nicotine were prevented by an alpha7 nicotinic acetylcholine receptor antagonist.

CONCLUSION

We conclude that the profibrotic response to nicotine in canine atrium is critically dependent upon downregulation of miR-133 and miR-590.

Molecular imaging-assisted optimization of hsp70 expression during laser-induced thermal preconditioning for wound repair enhancement

Patients at risk for impaired healing may benefit from prophylactic measures aimed at improving wound repair. Several photonic devices claim to enhance repair by thermal and photochemical mechanisms. We hypothesized that laser-induced thermal preconditioning would enhance surgical wound healing that was correlated with hsp70 expression. Using a pulsed diode laser (lambda=1.85 microm, tau(p)=2 ms, 50 Hz, H=7.64 mJ cm(-2)), the skin of transgenic mice that contain an hsp70 promoter-driven luciferase was preconditioned 12 hours before surgical incisions were made. Laser protocols were optimized in vitro and in vivo using temperature, blood flow, and hsp70-mediated bioluminescence measurements as benchmarks. Biomechanical properties and histological parameters of wound healing were evaluated for up to 14 days. Bioluminescent imaging studies indicated that an optimized laser protocol increased hsp70 expression by 10-fold. Under these conditions, laser-preconditioned incisions were two times stronger than control wounds. Our data suggest that this molecular imaging approach provides a quantitative method for optimization of tissue preconditioning and that mild laser-induced heat shock may be a useful therapeutic intervention prior to surgery.

Human embryonic stem cell-derived cardiomyocytes: inducing strategies

Cell-based therapy is emerging as an innovative approach for the treatment of degenerative diseases, and stem cells appear to be an ideal source of cells for this. In cardiology, in particular, human embryonic stem cell (hESC)-derived cardiomyocytes theoretically fulfill most, if not all, of the properties of an ideal donor cell, but several critical obstacles need to be overcome. Many research projects are focusing on set-up strategies for directing hESC differentiation toward the cardiac lineage. It is one of the main difficulties in the search to provide a valuable source of cells to effect regeneration of myocardial tissue in patients with severe heart failure. To date, there are no easy and efficient protocols for the induction of hESC differentiation toward the cardiac lineage. Discovering new molecules or tools capable of doing this is imperative.

Neuroprotective effects of melatonin upon the offspring cerebellar cortex in the rat model of BCNU-induced cortical dysplasia

Cortical dysplasia is a malformation characterized by defects in proliferation, migration and maturation. This study was designed to evaluate the alterations in offspring rat cerebellum induced by maternal exposure to carmustine-[1,3-bis (2-chloroethyl)-1-nitrosoure] (BCNU) and to investigate the effects of exogenous melatonin upon cerebellar BCNU-induced cortical dysplasia, using histological and biochemical analyses. Pregnant Wistar rats were assigned to five groups: intact-control, saline-control, melatonin-treated, BCNU-exposed and BCNU-exposed plus melatonin. Rats were exposed to BCNU on embryonic day 15 and melatonin was given until delivery. Immuno/histochemistry and electron microscopy were carried out on the offspring cerebellum, and levels of malondialdehyde and superoxide dismutase were determined. Histopathologically, typical findings were observed in the cerebella from the control groups, but the findings consistent with early embryonic development were noted in BCNU-exposed cortical dysplasia group. There was a marked increase in the number of TUNEL positive cells and nestin positive cells in BCNU-exposed group, but a decreased immunoreactivity to glial fibrillary acidic protein, synaptophysin and transforming growth factor beta1 was observed, indicating a delayed maturation, and melatonin significantly reversed these changes. Malondialdehyde level in BCNU-exposed group was higher than those in control groups and melatonin decreased malondialdehyde levels in BCNU group (P<0.01), while there were no significant differences in the superoxide dismutase levels between these groups. These data suggest that exposure of animals to BCNU during pregnancy leads to delayed maturation of offspring cerebellum and melatonin protects the cerebellum against the effects of BCNU.

Effect of combined spa-exercise therapy on circulating TGF-β1 levels in patients with ankylosing spondylitis

BACKGROUND

Ankylosing spondylitis (AS) is a chronic inflammatory disease of the axial joints with no satisfactory therapy. Reduction of joint pain has been reported after a course of therapy at a spa, Gasteiner Heilstollen, in Badgastein in Austria. The mechanism underlying this beneficial effect is not clearly understood and objective evidence for the biological response to therapy is lacking. The aim of this study was to find evidence for a biological response to speleotherapy in patients with AS and to study the involvement of the antiinflammatory cytokine TGF-beta1 in this response.

PATIENTS AND METHODS

83 patients with AS were treated in Badgastein for 3-4 weeks. Therapy included active exercises, hyperthermia and exposure to low doses of radon in a former mine. Response to therapy was assessed from measurement of morning pain and immunoassay of serum levels of TGF-beta1 before and after therapy. Ten AS patients who received conventional therapy and 10 patients with low back pain (LBP) served as controls.

RESULTS

A significant increase in TGF-beta1 (total and active) was found in AS patients after spa therapy. Mean concentration of total TGF-beta1 increased from 28,715 pg/ml to 43,136 pg/ml, (P<0.01) and active TGF-beta1 increased from 77 pg/ml to 1096 pg/ml (P<0.001). When the AS patients were divided into two groups according to pain reduction, group 1 (decrease in morning pain, responders: n=46) exhibited a 17-fold increase of active TGF-beta1 levels (96 pg/ml to 1654 pg/ml, P<0.0001) whereas group 2 (no change or an increase in morning pain: nonresponders: n=37), showed only 7-fold increase (53 pg/ml to 402 pg/ml, P<0.01). There was a moderate increase in active TGF-beta1 from 31 pg/ml to 42 pg/ml (P<0.05) in patients with LBP and no significant change was observed in the patients treated with conventional therapy.

CONCLUSION

These results demonstrate a significant increase in circulating TGF-beta1 in patients with AS after the combined spa-exercise therapy in Badgastein. The results also provide evidence for a biological response to speleotherapy and suggest that TGF-beta, through its antiinflammatory function, may play a role in this response.

Invited review: Effects of heat and cold stress on mammalian gene expression

This review examines the effects of thermal stress on gene expression, with special emphasis on changes in the expression of genes other than heat shock proteins (HSPs). There are approximately 50 genes not traditionally considered to be HSPs that have been shown, by conventional techniques, to change expression as a result of heat stress, and there are <20 genes (including HSPs) that have been shown to be affected by cold. These numbers will likely become much larger as gene chip array and proteomic technologies are applied to the study of the cell stress response. Several mechanisms have been identified by which gene expression may be altered by heat and cold stress. The similarities and differences between the cellular responses to heat and cold may yield key insights into how cells, and by extension tissues and organisms, survive and adapt to stress.

Expression of transforming growth factor-beta isoforms and their receptors in chronic tendinosis

Chronic tendon lesions are degenerative conditions and may represent a failure to repair or remodel the extracellular matrix after repeated micro-injury. Since TGF-beta is strongly associated with tissue repair, we investigated the expression of TGF-beta isoforms (beta1, beta2 and beta3) and their 2 signalling receptors (TGF-betaRI and TGF-betaRII) in normal and pathological Achilles tendons. In all tissues, all 3 TGF-beta isoforms and the 2 receptors were present at sites of blood vessels. Cells in the matrix showed no staining for TGF-beta1 or beta3, while TGF-beta2 was associated with cells throughout the normal cadaver tendon. Tissue from tendons with pathological lesions showed an increase in cell numbers and percentage TGF-beta2 expression. TGF-betaRII showed a wide distribution in cells throughout the tissue sections. As with TGF-beta2, there was an increase in the number of cells expressing TGF-betaRII in pathological tissue. TGF-betaRI was restricted to blood vessels and was absent from the fibrillar matrix. We conclude that despite the presence and upregulation of TGF-beta2, TGF-beta signalling is not propagated due to the lack of TGF-betaRI. This might explain why chronic tendon lesions fail to resolve and suggests that the addition of exogenous TGF-beta will have little effect on chronic tendinopathy.

Heat shock response is associated with protection against acute interstitial pancreatitis in rats

We recently reported that hyperthermia induces pancreatic expression of heat shock proteins (HSPs), particularly HSP70 isoforms, and protects against cerulein pancreatitis. We have now studied whether a double hyperthermia amplifies these effects and whether hyperthermia also protects against dibutyltin dichloride (DBTC)-induced pancreatitis. A further aim was to examine whether hyperthermia induces changes in transforming growth factor-beta1 (TGF-beta1). Following pretreatment without or with a single or double hyperthermia, pancreatitis was induced by application of cerulein or DBTC. Pancreatic HSP and TGF-beta1 expression were studied by immunoblotting. Pancreas injury was assessed by light microscopy and serum pancreatic enzyme activity. Hyperthermia as well as DBTC induced HSP72, whereas cerulein did not. A double hyperthermia led to a further increase in HSP72 compared to a single heat stress. In both models, hyperthermia significantly reduced pancreatic injury. Although a double hyperthermia slightly decreased the severity of cerulein pancreatitis compared to a single heat treatment, an improved pancreas protection against DBTC cytotoxicity was not achieved. We also found that hyperthermia induces the expression of TGF-beta1. In conclusion, hyperthermia preconditioning exerts protective effects against two pathophysiologically different types of pancreatitis by a mechanism that involves the up-regulation of HSP70 isoforms as well as TGF-beta1.

Induction of cardiac fibrosis by transforming growth factor-beta(1)

The role of transforming growth factor-beta(1) (TGF-beta(1)) in the production and deposition of collagens and in the induction of gene expression in the myocardium in relation to the development of myocardial fibrosis will be discussed. Very low expression of TGF-beta(1) and collagen type I and III mRNA is seen in the normal rat heart. Both expressions are markedly increased in the infarcted heart and the levels of TGF-beta(1) mRNA precedes increases in mRNA levels for extracellular matrix (ECM) proteins, suggesting a possible role of TGF-beta(1) in remodeling processes in the myocardium. The TGF-beta(1) expression is normally only transient since continuous TGF-beta(1) overexpression seems to promote nonadaptive cardiac hypertrophy and myocardial fibrosis. In vitro, TGF-beta(1) induces an increase in collagen production and secretion and enhances the abundance of mRNA levels for collagen type I and III in rat cardiac fibroblasts in culture. TGF-beta(1) also stimulates in vivo the expression of ECM proteins and in vivo gene transfer of TGF-beta(1) can induce myocardial fibrosis. Increased myocardial TGF-beta(1) and ECM protein mRNA are found in myocardial fibrosis induced by angiotensin II infusion, by noradrenaline treatment, by isoprenaline infusion, and by long-term blockade of NO synthesis. In vivo antagonism of TGF-beta(1) by neutralizing anti-TGF-beta(1) antibodies or by proteoglycans prevents the increase in gene expression of ECM proteins and inhibits myocardial fibrosis, suggesting that the increases in matrix protein production and fibrosis are mediated by TGF-beta(1).

Cardiac fibroblasts arrest at the G1/S restriction point in response to interleukin (IL)-1beta. Evidence for IL-1beta-induced hypophosphorylation of the retinoblastoma protein

Although responsible for only approximately one-third of the overall myocardial mass, the interstitial fibroblasts of the heart serve a fundamental role in establishing the functional integrity of myocardium and are the major source of myocardial extracellular matrix production. Their importance in clinical medicine is underscored by the observation that fibroblast numbers increase in response to several pathologic circumstances that are associated with an increase in extracellular matrix production, such as long standing hypertension and myocardial injury/infarction. Up to the present time, however, there has been little information available on either the kinetics of the cardiac fibroblast cell cycle, or the fundamental mechanisms that regulate its entry into and exit from the cell cycle. Previous work from our laboratory examining the effects of interleukin (IL)-1beta on myocardial growth and gene expression in culture indicated that cardiac fibroblasts have a diminished capacity to synthesize DNA in response to mitogen in the presence of this cytokine. The mechanism of IL-1beta action was not clear, however, and could have resulted from action at several different points in the cell cycle. The investigations described in this report indicate that IL-1beta exerts its effect on the fibroblast cell cycle at multiple levels through altering the expression of cardiac fibroblast cyclins, cyclin-dependent kinases, and their inhibitors, which ultimately affect the phosphorylation of the retinoblastoma gene product.

Dietary salt enhances glomerular endothelial nitric oxide synthase through TGF-beta1

Dietary salt controls production of nitric oxide (NO), a potent paracrine relaxation factor involved in glomerular filtration and salt excretion. We hypothesized that glomerular NO production was enhanced through endothelial nitric oxide synthase (NOS3). Rats in metabolic cages were studied after 4 days on 0.3% (Lo-salt) or 8.0% (Hi-salt) NaCl diet. Steady-state mRNA and protein levels of NOS3 and calcium-dependent NO production of isolated glomeruli from Hi-salt animals were greater than those values observed in glomeruli from Lo-salt rats. Because dietary salt enhanced glomerular production of transforming growth factor-beta1 (TGF-beta1) [W.-Z. Ying and P. W. Sanders. Am. J. Physiol. 274 (Renal Physiol. 43): F635-F641, 1998], studies were then conducted to examine the interaction between NOS3 and TGF-beta1. Glomerular steady-state levels of mRNA of NOS3 and TGF-beta1 directly correlated (r2 = 0. 946; P < 0.0001). A neutralizing antibody to TGF-beta reduced NOS3 protein and NO production in cultured glomeruli from Hi-salt animals to levels seen in the Lo-salt glomeruli. Thus dietary salt increased glomerular expression of TGF-beta1, which in turn augmented NO production through NOS3.

Dietary salt modulates renal production of transforming growth factor-beta in rats

Transforming growth factors (TGF) are potent multifunctional polypeptides that are involved in renal function and glomerular sclerosis. We postulated that dietary salt modified renal production of TGF-beta. An increase in dietary salt produced sustained increases in steady-state levels of mRNA for TGF-beta 1, -beta 2, and -beta 3 in the rat kidney. While serum concentration of TGF-beta 1 did not change, the 8.0% NaCl diet increased urinary excretion of TGF-beta 1, indicating enhanced renal production was the source of TGF-beta 1. Increasing urinary flow rates with diuretics did not further increase synthesis of TGF-beta 1 in animals receiving the 8.0% NaCl diet. The 8.0% NaCl diet increased production of TGF-beta 1 in both glomeruli and tubules, although active TGF-beta 1 was secreted in greater amounts only from glomeruli. Enhanced glomerular production of both inactive and active TGF-beta 1 induced by the 8.0% NaCl diet was inhibited by tetraethylammonium (TEA) and not glybenclamide. Cardiac production of TGF-beta 1 also increased on the 8.0% NaCl diet but was not affected by TEA. The results demonstrated that increased dietary salt augmented glomerular TGF-beta production by a mechanism that included a TEA-sensitive potassium channel. Dietary salt, by facilitating glomerular expression of TGF-beta, may directly promote development of glomerulosclerosis.

Heat shock of human synovial and dermal fibroblasts induces delayed up-regulation of collagenase-gene expression

We investigated the effect of heat shock on the expression of the collagenase gene in normal human synovial and dermal fibroblasts. Heat shock (42-44 degrees C for 1 h) caused a marked increase in heat-shock protein 70 (HSP-70) mRNA levels, followed by a delayed increase in collagenase mRNA levels, in both cell types. Pretreatment with cycloheximide had no effect on the heat-shock-induced increase in HSP-70 mRNA expression, but abrogated the induction of collagenase mRNA during the recovery. To study the mechanisms of collagenase-gene induction by heat shock, the transcriptional activity of a collagenase-promoter-driven chloramphenicol acetyltransferase (CAT) reporter gene was examined in transient transfection experiments. Heat shock was followed by a > 2-fold increase in CAT activity driven by a 3.8 kb fragment of the collagenase promoter, or by a construct containing an AP-1 binding site. A mutation in the AP-1 binding site abolished the effect of heat shock. Electrophoretic-mobility-shift assays revealed a marked increase in DNA-binding activity specific for the AP-1 binding site in nuclear extracts prepared from synovial fibroblasts recovering from heat shock. These results indicate that heat shock causes a delayed increase in collagenase-gene expression in human fibroblasts, and suggests that this stimulation involves, at least in part, transcriptional activation through an AP-1 binding site. Heat shock appears to initiate a programme of cellular events resulting in collagenase-gene expression, and therefore may contribute to connective-tissue degradation in disease states.