[The mechanism of inhibition of the increase in intracellular calcium concentration by the islet amyloid polypeptide in high glucose-stimulated INS-1 cells]

OBJECTIVE

To explore the potential mechanism of the inhibition of increased intracellular free calcium concentration ([Ca²⁺]i) by short-term exposure to the islet amyloid polypeptide (IAPP) in high glucose-stimulated pancreatic β cells.

METHODS

The pancreatic β cells were loaded with calcium sensitive fluorescent indicator Fluo-4/AM. The fluorescence intensity, which represented [Ca²⁺]i, was measured in time by laser scanning confocal microscope before and after stimulated by glucose, KCl, caffeine and carbachol.

RESULT

The fluorescence intensity F/F₀ in INS-1 cells, increased to about 2 folds after glucose stimulation. After the exposure to the IAPP with different concentration, the fluorescence intensity F/F₀ was decreased slightly in the pretreated cells by 16.7 mmol/L glucose with 0.5 µmol/L IAPP. However, after the pretreatment of IAPP with the concentration of 1.0, 5.0, 10.0 µmol/L, the fluorescence intensity F/F₀ showed a dose-dependent decrease with statistical difference. The fluorescence intensity F/F₀ in the cells increased rapidly in a peak pattern after the stimulation of 30 mmol/L KCl. But with the pretreatment of 10.0 µmol/L IAPP, the fluorescence intensity F/F₀ decreased with statistical difference. With 20 mmol/L caffeine and 100 µmol/L carbachol which stimulated Ca²⁺ release respectively from internal ryanodine receptor (RYR) and inositol triphosphate (IP₃) Ca²⁺ storage, the fluorescence intensity F/F₀ curve presented a peak pattern. After 10 µmol/L IAPP pretreatment, the fluorescence intensity F/F₀ showed no statistical difference from the control group.

CONCLUSIONS

The short-term effect of IAPP on pancreatic β cells has no influence on the caffeine and carbachol stimulated Ca²⁺ release from endoplasmic reticulum RYR and IP₃ Ca²⁺ storage. The inhibition of calcium increase in INS-1 cells by short-term exposure to IAPP may mainly via inhibiting the voltage-gated L-calcium channels with intact release capacity of Ca²⁺ storage.

[Risk factors for infections of methicillin-resistant Staphylococci in diabetic foot patients]

OBJECTIVE

To examine the distribution patterns of pathogens isolated from the patients with diabetic foot ulcers and explore the risk factors for infections of methicillin-resistant S. aureus (MRSA) or methicillin-resistant S. epidermidis (MRSE).

METHODS

A total of 388 diabetic-foot patients hospitalized at Tianjin Metabolic Diseases Hospital between January 2008 and June 2010 were recruited. The distribution profiles of pathogens isolated from diabetic foot ulcers were summarized. The patients with S. aureus infections were divided into MRSA and MSSA groups while those with S. epidermidis infections into MRSE and MSSE groups. The clinical features of these patients were compared between all groups. Logistic regression was employed to identify the risk factors for the MRSA/MRSE infections.

RESULTS

A total of 362 pathogens were isolated from them. And the Gram-positive bacteria were the most predominant (57.2%, 207/362), followed by Gram-negative bacilli (39.2%, 142/362) and true fungi (3.6%, 13/362). The three most frequently isolated pathogens were S. aureus (27.1%), S. epidermidis (18.8%) and Pseudomonas aeruginosa (15.5%). Statistically significant differences existed in antibiotic usage in 6 months prior to hospitalization, course of ulcer, ulcer size, deep ulcer, osteomyelitis, hypertension, anemia, hypoproteinemia and erythrocyte sedimentation rate between the patients infected with MRSA and MSSA (P < 0.05). The MRSE infection was correlated with recurrent ulcer, osteomyelitis, hypoproteinemia, HbA1c and lower total serum protein (P < 0.05). Multiple Logistic regression analysis revealed that antibiotic usage in 6 months prior to hospitalization, long course of ulcer, osteomyelitis, hypertension and hypoproteinemia were risk factors for the MRSA infection. And HbA1c was a risk factor for the MRSE infection.

CONCLUSION

In the present study, the Gram-positive cocci are the main pathogens isolated from diabetic foot ulcers. And S. aureus and S. epidermidis are the most frequently isolated pathogens. Antibiotic usage in 6 months prior to hospitalization, long course of ulcer, osteomyelitis, hypertension and hypoproteinemia are risk factors for the MRSA infection. And HbA1c is a risk factor for the MRSE infection.

IL-17RA aptamer-mediated repression of IL-6 inhibits synovium inflammation in a murine model of osteoarthritis

OBJECTIVE

Generate DNA aptamers to inhibit IL-17RA-mediated synovial inflammation in an experimental mouse model of osteoarthritis (OA).

METHODS

A novel cell-SELEX method was applied to obtain DNA aptamers specific for IL-17RA. A single-stranded (ss) DNA library with four(30) probes was synthesised. By incubating this library with NIH3T3 cells, we collected DNA ligands that could bind the cell surface. The collected ligands were incubated with IL-17RA-deficient NIH3T3 cells, and unbound ssDNA was harvested from the supernatant for the next round of selection. After 12 cycles, specific aptamers against IL-17RA were generated. For animal experiments, a meniscectomy was performed on Balb/C mice to generate an animal model of OA. Mice received weekly intra-articular (i.a.) injections of aptamers or control treatments for 6 weeks. Synovial membranes were evaluated by histomorphology and the mRNAs of critical inflammatory cytokines were measured by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

An aptamer termed RA10-6 was obtained that could efficiently block IL-17 binding to IL-17RA in a dose-dependent manner in vitro. Histological examination and quantitative RT-PCR results showed that OA mice that injected with RA10-6, especially in combination with celecoxib demonstrated inhibition of synovial thickening and reduction in IL-6 levels in the synovial tissue.

CONCLUSION

Our results suggest that RA10-6 can inhibit synovial inflammation by blocking IL-17/IL-17RA-mediated IL-6 expression. RA10-6 acted synergistically with celecoxib to inhibit IL-6 expression in synovial tissues. Thus, aptamers targeting IL-17RA might serve as potent adjunctive agents for the early treatment of OA.

Association of ATP1A1 gene polymorphism with heat tolerance traits in dairy cattle

Heat stress produces oxidative stress and affects the alternation of plasma K(+) and Na(+). Since Na(+),K(+)-ATPase is sensitive to oxidative stress and critical for maintaining the homeostasis of these two ions, we examined the genetic polymorphism of the ATP1A1 gene in 160 Holstein cows using polymerase chain reaction low ionic strength single-strand conformation polymorphism and DNA sequencing methods. G to A at position -14103 in exon 14 and C to T at position -14242 in intron 14 of the bovine ATP1A1 gene were identified, but the former single nucleotide polymorphism was silent with respect to the amino acid sequence of the protein. However, we found significant correlations between ATP1A1 gene polymorphism and the coefficient of heat tolerance (P<0.01) and with respiratory rate (P<0.01). Genotype AC was the most favorable genotype for heat tolerance. This polymorphism site has potential as a genetic marker for heat tolerance traits in dairy cattle breeding.

P-glycoprotein regulating biphasic insulin secretion in rat pancreatic beta cells

BACKGROUND

A 65-kD mdr1 (multi-drug resistance protein 1, P-glycoprotein)-like protein has been suggested to be the regulatory protein to the chloride channel protein 3 (ClC-3) mediating insulin granules acidification and release in mouse pancreatic beta cells. But the protein has not been deeply investigated. In this study, we identified existence of the 65-kda protein in rat islets and preliminarily explored its biological functions.

METHODS

Total RNAs of rat kidneys served as positive controls, and pancreas, islets and INS-1 cells were extracted for reverse-transcript PCR (RT-PCR), respectively. The cDNAs were run with specific primers selected from the mRNA of abcb1b encoding P-glycoprotein. All PCR products were visualized in agarose gel electrophoresis and sequenced. Homogenates of rat islets and INS-1 cells were applied to SDS-PAGE. P-glycoprotein was detected by a specific monoclonal antibody, C219. Biphasic insulin release was measured in static incubations of rat islets with radioimmunology assay.

RESULTS

Compared with positive control, expression of the P-glycoprotein mRNA segments were detected in the islets, INS-1 cells and pancreas. Sequence analysis confirmed that the PCR products were matched with mRNA of P-glycoprotein. A 65-kda protein was recognized by the antibody in the islets homogenate but not in that of INS-1 cells in Western-blotting. Instead, the homogenate of INS-1 cells contained a 160-kda protein recognized by the antibody. Insulin secretion of rat islets were stimulated by high glucose (16.7 mmol/L), and showed biphasic curve during 60-minute incubation. After co-incubation with cyclosporine A (CsA), specific inhibitor to P-glycoprotein, the second phase of insulin secretion was reduced significantly while the first phase was not influenced.

CONCLUSIONS

The 65-kda protein expressed in rat islets is most likely a mini-P-glycoprotein. It may play a key role regulating biphasic insulin release.

[Ecosystem service valuation of Ertan Reservoir watershed in mitigating reservoir sand sedimentation]

By using software ArcGIS 9.2, an evaluation model was established to simulate the ecosystem service of Ertan Reservoir watershed in mitigating the sand sedimentation in the reservoir. In the meantime, sediment delivery ratio and universal soil loss equation were used to simulate the spatial patterns of the annual sediment yield and sediment retention in the watershed as well as the value during the service life period. In 2000, the total quantity of soil retention in the watershed was 12. 1 x 10(8) t x a(-1). The region with higher soil retention was near the main and branch streams of Yalong River, and that with higher sediment delivery ratio was near the streams and the Ertan Reservoir. The region with higher sediment yield and sediment retention was around the reservoir. The actual sediment yield in the study area was 629.3 x 10(4) t x a(-1), occupying 12.7% of the actual soil erosion volume. Farmland was the most important source of sediment yield, with its sediment yield occupying 62.9% of the total. The contribution of forestland to the mitigation of reservoir sand sedimentation was higher than that of the other lands on a per unit area basis. For the reservoir's designed operating life (100 a), the total value of the watershed in the service of mitigating Ertan Reservoir sand sedimentation was 2.75 billion yuan.

Effects and mechanism of glucagon-like peptide-1 on injury of rats cardiomyocytes induced by hypoxia-reoxygenation

BACKGROUND

Although the insulinotropic role of glucagon-like peptide-1 (GLP-1) in type 2 diabetes mellitus has been substantiated, its role in cardioprotection remains largely unknown. This study aimed to determine the effects of GLP-1 on injury of rats cardiac myocytes induced by hypoxia-reoxygenation (H/R) and the possible mechanisms.

METHODS

The cultured neonatal rats cardiac myocytes were randomly divided into seven groups: the normal control group, the H/R group, the GLP-1 + H/R group, the GLP-1 + H/R + UO126 (the p42/44 mitogen-activated protein kinase (MAPK) inhibitor) group, the GLP-1 + H/R + LY294002 (phosphatidylinositol 3-kinase (PI3K) inhibitor) group, the H/R + UO126 group, and the H/R + LY294002 group. The lactate dehydrogenase (LDH) activity, apoptosis rate of cardiac myocytes, and caspase-3 activity were detected after the injury of H/R.

RESULTS

Compared with the normal control group, the activity of LDH, cardiac myocyte apoptosis rate, and caspase-3 activity all increased significantly in the H/R group (P < 0.01). Compared with the H/R group, these three indices all decreased in the H/R + GLP-1 group (P < 0.01). However, the changes of LDH activity, apoptosis rate, and caspase-3 activity were inhibited by LY294002 and UO126 respectively.

CONCLUSIONS

GLP-1 can directly act on cardiac myocytes and protect them from H/R injury mainly by inhibiting their apoptosis. Its mechanism may be through the PI3K-Akt pathway and the MAPK signaling pathway.

Baseline concentrations and spatial distribution of trace metals in surface soils of Guangdong province, China

A total of 260 surface soil samples were collected to investigate the spatial distribution of trace metals in Guangdong province, one of the fast developing regions in China. The results show that the upper baseline concentrations of Cu, Pb, Zn, Cd, Ni, Cr, and Hg were 28.7, 57.6, 77.8, 0.13, 23.5, 87.0, and 0.15 mg kg(-1), respectively. Regional parent materials and pedogenesis are the primary factors influencing the concentrations of trace metals, and various anthropogenic activities are the second most important factors. The spatial distribution of trace metals is correlated to the geological characters with high concentrations of trace metals always located in regional fault areas, basins, and the Pearl River Delta alluvial plain and to the low concentrations associated with the other areas in Guangdong province.

Spatial distribution and vertical variation of arsenic in Guangdong soil profiles, China

Total of 260 soil profiles were reported to investigate the arsenic spatial distribution and vertical variation in Guangdong province. The arsenic concentration followed an approximately lognormal distribution. The arsenic geometric mean concentration of 10.4 mg/kg is higher than that of China. An upper baseline concentration of 23.4 mg/kg was estimated for surface soils. The influence of soil properties on arsenic concentration was not important. Arsenic spatial distributions presented similar patterns that high arsenic concentration mainly located in limestone, and sandshale areas, indicating that soil arsenic distribution was dependent on bedrock properties than anthropogenic inputs. Moreover, from A- to C-horizon arsenic geometric mean concentrations had an increasing tendency of 10.4, 10.7 to 11.3 mg/kg. This vertical variation may be related to the lower soil organic matter and soil degradation and erosion. Consequently, the soil arsenic export into surface and groundwaters would reach 1040 t year-1 in the study area.

[Structural modification and bioactivity of cyclovirobuxine D]

AIM

To search for new compounds for the treatment of cardiovascular diseases by structural modification of cyclovirobuxine D.

METHODS

According to rational drug design principle, a series of cyclovirobuxine D analogues were prepared, and their bioactivities were tested.

RESULTS

Ten new compounds were syntheized and confirmed by spectra.

CONCLUSION

Endurance lacking oxygen activity and antiarrhythmia effects of some analogues of cyclovirobuxine D were tested. Some compounds showed better activity than cyclovirobuxine D.

[Histomorphometric analysis in ovariectomized rat with osteoporosis]

OBJECTIVE

To establish the pattern of bone loss of Sprague-Dawley rats after ovariectomy, to investigate and assess the pattern of bone remodeling in ovariectomized rats and the therapeutic action of nilestriol and levenorgestrel.

METHODS

Histomorphometric analysis for bone tissues was performed with the instrument of computerized image analysis.

RESULTS

The trabecular bone volume, mean trabecular thickness, and trabecular bone perimeter were all significantly decreased (P < 0.01) in ovariectomized rats in the 14th week postsurgery compared to the sham operated group. But the osteoblastic index, osteoclastic index, resorptive surface of trabecular, and trabecular surface covered by osteoblast were significantly increased (P < 0.01). There was no significant difference between the treatment group and the sham operated group.

CONCLUSIONS

The pattern of bone loss of rats after ovariectomy has been established successfully. The study provides evidence that the cause of bone loss in the ovariectomized rats is attributable to the increase of bone turnover and negative imbalance in bone remodeling process. The treatment of nilestriol and levenorgestrel may decrease the bone turnover and correct the imbalance to cure the osteoporosis.

Regulation of MMP-9 production by human corneal epithelial cells

The matrix metalloproteinases, MMP-2 and MMP-9, are known to be critical extracellular-remodeling enzymes in wound healing and other diseases of the ocular surface. This study investigated the regulation of MMP-2 and MMP-9 in human corneal epithelial cells by growth factors and pro-inflammatory cytokines (IL-1beta and TNF-alpha) they are exposed to, and by doxycycline, a medication used to treat ocular surface disease. Primary human corneal epithelial cell cultures were treated with one of the following cytokines (IL-1alpha, IL-1beta, IL-6, IL-8, TNF-alpha) or growth factors (EGF, HGF, KGF, PDGF-BB, TGF-alpha, TGF-beta), with or without their corresponding inhibitors. The conditioned media were collected after 24 hr for gelatin zymography and MMP-9 activity assay. Total RNA was extracted from the cells treated for 6 hr and was subjected to RT-PCR and Northern hybridization. Between the two gelatinases, MMP-2 and MMP-9, detected by zymography, the 92 kDa MMP-9 in the conditioned medium was markedly up-regulated by the pro-inflammatory cytokines, IL-1beta and TNF-alpha. The MMP-9 protein and activity were dose-dependently stimulated by IL-1beta or TNF-alpha at 0.1, 1.0 and 10 ng ml(-1). This up-regulation was nearly abolished by neutralizing antibodies (IL-1beta and TNF-alpha) and by IL-1 receptor antagonist. Semi-quantitative RT-PCR and Northern hybridization disclosed that the MMP-9 transcript was also markedly up-regulated in a dose-dependent manner by IL-1beta and TNF-alpha. Doxycycline (10 microg ml(-1)) suppressed MMP-9 protein level and activity, but not its mRNA, that was stimulated by IL-1beta and TNF-alpha (1 ng ml(-1)). In contrast, the 72 kDa MMP-2 was not significantly modulated by any of these cytokines. In conclusion, production of MMP-9 is stimulated by the pro-inflammatory cytokines, IL-1beta and TNF-alpha. These factors may play a role in the pathogenesis of MMP-9 mediated corneal matrix degradation. The efficacy of doxycycline in treating ocular surface diseases may be related to its ability to suppress MMP-9 production in the corneal epithelium.

Binding of human clusterin by Staphylococcus epidermidis

To hypothesise that Staphylococcus epidermidis may possess clusterin receptor(s), bacterial binding of human clusterin was determined. In a fluid phase, the binding was markedly influenced by culture medium and three out of 12 S. epidermidis strains grown on ISO-sensitest agar expressed clusterin-binding ability. S. epidermidis J9P, selected for further study, showed saturable binding of iodine-labelled clusterin, and the binding was only inhibited by unlabelled clusterin. The binding was sensitive to protease treatment. Scatchard plot indicated one single class of binding sites (K(d)=104.2 nM). None of the S. epidermidis strains bound immobilised clusterin. These data imply that ligand-receptor interaction exists between S. epidermidis and clusterin in fluid phase, but the domain(s) recognised by bacteria may have been occluded when clusterin was adsorbed on a surface.

Binding of vitronectin and clusterin by coagulase-negative staphylococci interfering with complement function

Coagulase-negative staphylococci (CoNS) are commonly associated with infections of prosthetic devices mediated by adsorbed host factors on biomaterial surfaces. Complement activation is known to occur and induce unspecific inflammation around the biomaterials. Human vitronectin (Vn) and clusterin (Clu), two potent inhibitors of complement, can be bound by CoNS. With a hypothesis whether binding of Vn or Clu influences complement activation, two measurements were determined. For Vn, complement activation was measured with a mouse anti-activated human C9 antibody. In the presence of Vn-binding strain, Staphylococcus hemolyticus SM13I, complement activation on a surface pre-coated with Vn occurred as it did in the absence of Vn pre-coating. For S. epidermidis 3380, which does not express binding of Vn, complement activation on a Vn-presented surface was significantly decreased. For Clu, erythrocytes lysis was measured to reflect the end product of complement activation (membrane attack complex). The complement-induced hemolysis increased when human serum was pre-incubated with Clu-binding strains, S. epidermidis J9P. The enhancement of hemolysis by J9P decreased when serum was supplemented by exogenous Clu. The data imply that interaction between CoNS and Vn or Clu interferes with one of their physiological functions, complement inhibition.

Characterization of vitronectin-binding proteins of Staphylococcus epidermidis

Staphylococcus epidermidis is the most common microorganism that is isolated from the cerebrospinal fluid (CSF) shunt infection patients. Vitronectin adsorbed on the surface of implants may mediate bacterial adhesion and colonization. To characterize vitronectin-binding properties, we analyzed S. epidermidis BD5703 isolated from a CSF shunt infection. Expression of vitronectin-binding protein(s) depended on culture media. Two proteins (60 and 52 kDa) were purified from vitronectin affinity chromatography. Two other vitronectin-binding proteins (21 and 16 kDa) were purified from an ion-exchange column. All purified proteins blocked bacterial binding of immobilized vitronectin significantly except the 16-kDa protein. The N-terminal sequences of the 21- and 16-kDa proteins did not show any appreciable amino acid sequence homology. The 52-kDa protein was sequenced by mass spectrometry and identified as an autolysin. This report demonstrates that interaction of vitronectin with multiple recognition sites on BD5703 surface may contribute to bacterial colonization.

The effect of KSCN on the partition of proteins in polyethylene glycol/(NH4)2SO4 aqueous two-phase system

The effect of potassium thiocyanate on the partitioning of lysozyme and BSA in polyethylene glycol 2000/ammonium sulfate aqueous two-phase system has been investigated. As a result of the addition of potassium thiocyanate to the PEG/ammonium sulfate system, the PEG/mixed salts aqueous two-phase system was formed. It was found that the potassium thiocyanate could alter the pH difference between the two phases, and, thus, influence the partition coefficients of the differently charged proteins. The relationship between partition coefficient of the proteins and pH difference between two phases has been discussed. It was proposed that the pH difference between two phases could be employed as the measurement of electrostatic driving force for the partitioning of charged proteins in polyethylene 2000/ammonium sulfate aqueous two-phase system.

Overexpression of collagenase (MMP-1) and stromelysin (MMP-3) by pterygium head fibroblasts

BACKGROUND

The balance between matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs) determines the extent of connective tissue degradation and remodeling.

OBJECTIVE

To determine whether pterygium, characterized by fibrovascular invasion into the cornea, may in part be mediated by an increased activity of MMPs.

MATERIALS AND METHODS

Expression of transcripts and proteins of MMPs, TIMPs, and urokinase plasminogen activator (uPA) by cultured human pterygium head, body, and subconjunctival fibroblasts, and normal corneal and conjunctival fibroblasts were determined by Northern hybridization, enzyme-linked immunosorbent assay, Western blotting, zymography, and quantitative collagenase assay, respectively.

RESULTS

Compared with normal conjunctival fibroblasts from 6 subjects, the expression of MMP-1 and MMP-3 transcripts was dramatically increased in pterygium head fibroblasts of 8 patients, but not in pterygium body fibroblasts of 6 patients. The protein levels and collagenolytic and caseinolytic activities of MMP-1 and/or MMP-3 were also markedly increased in pterygium head fibroblasts. The MMP-1 and MMP-3 proteins and activity decreased in order from pterygium head to body to subconjunctival fibroblasts. There was no difference in the transcript and protein expression of MMP-2, TIMP-1, TIMP-2, and uPA among these groups.

CONCLUSION

Pterygium head fibroblasts express increased mRNA, protein, and activities of MMP-1 and MMP-3.

CLINICAL RELEVANCE

Overexpression of MMP-1 and MMP-3, a phenotype previously linked with UV exposure in dermal fibroblasts to explain the pathologic finding of elastotic degeneration, suggests that pterygium head fibroblasts might be intrinsically altered by UV, which might be responsible for corneal invasion.

Regulation of collagenase, stromelysin, and gelatinase B in human conjunctival and conjunctivochalasis fibroblasts by interleukin-1beta and tumor necrosis factor-alpha

PURPOSE

Overexpression and increased activities of matrix metalloproteinases (MMPs) have recently been reported in cultured conjunctival fibroblasts from patients with conjunctivochalasis. The role of inflammatory cytokines in modulating expression of MMPs, their tissue inhibitors (TIMPs), and urokinase plasminogen activator (uPA) as potential contributors to the pathogenesis of conjunctivochalasis was investigated.

METHODS

Interleukin-1beta (IL-1beta) or tumor necrosis factor-alpha (TNF-alpha) was added at 10 ng/ml to a serum-free medium. Expression of transcripts and proteins of MMPs, TIMPs, and uPA by cultured normal human conjunctival and conjunctivochalasis fibroblasts was determined by Northern hybridization, enzyme-linked immunosorbent assay (ELISA) and Western blot analysis, respectively. Gelatin and casein zymographies were performed in serum-free conditioned media with and without the respective enzyme inhibitors.

RESULTS

Without challenging the cells, conjunctivochalasis fibroblasts showed mRNA and protein overexpression of MMP-1 and MMP-3 compared with normal conjunctival fibroblasts, which showed minor or no expression of these enzymes. IL-1beta markedly and TNF-alpha to lesser extent increased mRNA and protein expression of MMP-1 and MMP-3 in conjunctivochalasis fibroblasts from 2 subjects when compared with normal conjunctival fibroblasts from 2 subjects and with their nonstimulated counterparts. In conjunctivochalasis fibroblasts and normal conjunctival fibroblasts, TNF-alpha, but not IL-1beta, induced a gelatinolytic activity of MMP-9, which was further confirmed by Western blot analysis and ELISA. Expression of MMP-2, TIMP-1, and TIMP-2 mRNA and protein was not influenced by IL-1beta or TNF-alpha, and no difference was found in the gelatinolytic activity of MMP-2 between both cell types.

CONCLUSIONS

Inflammatory cytokines such as IL-1beta and TNF-alpha, which can potentially be derived from the ocular surface and tears, may be responsible for increased expression of MMPs in cultured conjunctivochalasis fibroblasts. Ocular inflammation might be one important denominator in the pathogenesis of conjunctivochalasis.

Doxycycline inhibition of interleukin-1 in the corneal epithelium

PURPOSE

To evaluate the effect of doxycycline on the regulation of interleukin (IL)-1 expression and activity in human cultured corneal epithelium.

METHODS

Human corneal limbal epithelium (HLE) was cultured from explants prepared from limbal rings of donor corneas. Primary cultured limbal epithelial cells were treated with either 10 microg/ml lipopolysaccharide (LPS), LPS with 10 microg/ml doxycycline, or LPS with 0.1 mg/ml methylprednisolone (MP) for 24 hours. The intracellular and supernatant protein amounts of IL-1alpha, the precursor and mature forms of IL-1beta, IL-1 receptor antagonist (IL-1 RA), and the intracellular level of IL-1beta-converting enzyme (ICE) were measured with enzyme-linked immunosorbent assays (ELISAs). Western blot analysis was performed to evaluate IL-1 RA protein. mRNA steady state amounts were determined by RNase protection assay (RPA) for IL-1alpha, IL-1beta, IL-1 RA, and ICE.

RESULTS

LPS increased the mRNA and protein amounts of intracellular and released IL-1alpha, mature IL-1beta, and IL-1 RA. Doxycycline inhibited the LPS-induced IL-1beta increase in the mRNA and protein amounts in the corneal epithelium and upregulated the expression of the anti-inflammatory IL-1 RA protein. In addition, doxycycline reduced the steady state level of the cellular ICE protein but did not affect the level of ICE transcripts. IL-1beta secreted to the conditioned media of HLE was functionally active in inducing matrix metalloproteinase (MMP)-1 and MMP-3 in cultured corneal fibroblasts. Doxycycline significantly decreased IL-1beta bioactivity in the supernatants from LPS-treated corneal epithelial cultures. These effects were comparable to those induced by the corticosteroid, MP.

CONCLUSIONS

Doxycycline can suppress the steady state amounts of mRNA and protein of IL-beta and decrease the bioactivity of this major inflammatory cytokine. These data may partially explain the clinically observed anti-inflammatory properties of doxycycline. The observation that doxycycline was equally potent as a corticosteroid, combined with the relative absence of adverse effects, makes it a potent drug for a wide spectrum of ocular surface inflammatory diseases.

Regulation of collagenase, stromelysin, and urokinase-type plasminogen activator in primary pterygium body fibroblasts by inflammatory cytokines

PURPOSE

To examine the expression patterns of extracellular matrix degrading enzymes in cultured primary pterygium body fibroblasts activated by cytokines and growth factors potentially derived from ocular surface epithelial cells and tears.

METHODS

EGF, TGF-alpha, PDGF-BB, IL-1beta, bFGF, TGF-beta1, TNF-alpha, or IL-6 were added at 10 ng/ml to early passaged primary pterygium body fibroblasts (PBF) or normal human conjunctival fibroblasts (HJF) in a serum-free medium. Expression of transcripts and proteins of MMP-1, MMP-2, MMP-3, MMP-9, TIMP-1, TIMP-2, and uPA was determined by Northern hybridization, ELISA, and Western blotting, respectively. Gelatin and casein zymographies were performed in their serum-free conditioned media with or without enzyme inhibitors to determine the activity of MMP-2 and -3, respectively.

RESULTS

IL-1beta and TNF-alpha dramatically increased the mRNA and protein expression of MMP-1 and MMP-3 in cultured PBF when compared to normal HJF and to their nonstimulated counterparts cultured in a serum-free medium. EGF and TGF-alpha also upregulated MMP-3 in PBF when compared to HJF. The transcript levels of MMP-2 were high but stable for the two cell types regardless of the cytokine treatment. Both TIMP-1 and TIMP-2 expressions were not influenced by the cell type or the cytokine treatment. MMP-9 was not expressed in either of these two types of fibroblasts. Both IL-1beta and TNF-alpha induced a significant decrease in uPA expression in PBF, whereas bFGF induced a slight increase in both HJF and PBF.

CONCLUSIONS

Chronic inflammatory stimulation by IL-1beta and TNF-alpha, which potentially can be derived from the ocular surface and tears, may be responsible for increased expression of MMPs in cultured PBF. These data have clinical implications on progression of pterygium and recurrence associated with incomplete excision of primary PBF under the influence of ocular surface inflammation. Suppression of intraoperative and postoperative inflammation may be a new strategy to prevent pterygium recurrence.

Detection of sialomucin complex (MUC4) in human ocular surface epithelium and tear fluid

PURPOSE

To evaluate human ocular surface epithelium and tear fluid for the presence of sialomucin complex (MUC4), a high-molecular-weight heterodimeric glycoprotein composed of mucin (ASGP-1) and transmembrane (ASGP-2) subunits.

METHODS

Reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis assays were used to identify sialomucin complex RNA in ocular surface epithelia. Immunoprecipitation and immunoblot analysis were used to identify immunoreactive species in human tears and in the corneal and conjunctival epithelia using antibodies specific for carbohydrate and peptide epitopes on the sialomucin complex subunits. Immunofluorescence staining was used to detect sialomucin complex in frozen sections and impression cytology specimens of human cornea and conjunctival epithelia.

RESULTS

ASGP-1- and ASGP-2-specific sequences were amplified from RNA extracted from both conjunctival and corneal epithelial biopsies by RT-PCR. Sialomucin complex transcripts were also detected in these tissues by Northern blot analysis, with a greater level of RNA detected in the peripheral than the central corneal epithelium. Sialomucin complex was immunoprecipitated from tear fluid samples and both corneal and conjunctival epithelia and detected by immunoblot analysis with specific anti-ASGP-1 and anti-ASGP-2 antibodies. The ASGP-1 peptide antibody HA-1 stained the full thickness of the corneal and conjunctival epithelia. In contrast, antibody 15H10, which reacts against a carbohydrate epitope on ASGP-1, stained only the superficial epithelial layers of these tissues. No staining was observed in the conjunctival goblet cells.

CONCLUSIONS

Sialomucin complex was originally identified in rat mammary adenocarcinoma cells and has recently been shown to be produced by the ocular surface epithelia of rats. Furthermore, it has been identified as the rat homologue of human MUC4 mucin. The present studies show that it is expressed in the stratified epithelium covering the surface of the human eye and is present in human tear fluid. Expression of a carbohydrate-dependent epitope on the mucin subunit (ASGP-1) of sialomucin complex occurs in a differentiation-dependent fashion. Sialomucin complex joins MUC1 as another membrane mucin produced by the human ocular surface epithelia but is also found in the tear fluid, presumably in a soluble form, as found on the rat ocular surface.

Suppression of TGF-beta signaling in both normal conjunctival fibroblasts and pterygial body fibroblasts by amniotic membrane

PURPOSE

When used as an alternative substrate following bare sclera removal of pterygium and other ocular surface diseases, amniotic membrane transplantation can reduce scarring on the reconstructed conjunctival surface. This study was carried out to determine if the amniotic membrane (AM) suppresses the expression of the TGFb signaling system in cultured normal conjunctival (HCF) and pterygial body fibroblasts (PBF).

METHODS

HCF and PBF were cultured on AM and plastic wells in serum-containing and serum-free DMEM with or without TGF-beta1. Total RNA was extracted and subjected to Northern hybridization with probes of TGF-beta1, b2 and b3; TGF-beta receptors (TGF- beta R) type I, II and III; a-smooth muscle actin (alpha-SM), b1-integrin, CD44, fibroblast growth factor receptor 1 (FGF-R1/ flg) and platelet-derived growth factor receptor b (PDGFR-beta); and GAPDH as a loading control. MTT assay was used for cell proliferation.

RESULTS

Amniotic membrane markedly suppressed the transcript expression of TGF-beta2, b3 and all three types of TGF-beta receptors by both fibroblasts as compared to their cultures on plastic surface. In addition, expression of CD44 transcript was also markedly suppressed while that of b1 integrin, a-SM actin, and FGFR1/flg was mildly suppressed. In contrast, expression of TGF-beta1 and PDGFR-beta remained largely unchanged. The cell proliferation of HCF and PBF grown on AM was also significantly suppressed.

CONCLUSIONS

Amniotic membrane matrix uniquely suppresses TGF- beta signaling in both types of fibroblasts. It may also suppress signaling via CD44, b1 integrin and FGFR1/flg. As a result, the phenotype may become less mitogenic, contractile and fibrogenic. These data support in part why amniotic membrane transplantation has an anti-scarring effect for conjunctival surface reconstruction.

Polychlorinated dibenzo-p-dioxins and dibenzofurans in sediment, soil, fish, shellfish and crab samples from Tokyo Bay area, Japan

Concentrations of tetra- to octa-chlorinated dibenzo-p-dioxins and dibenzofurans in samples collected in or near Tokyo Bay, Japan, with a densely inhabited catchment area, were congener-specifically determined and discussed. Analyzed in this study were samples of surface sediment covering the whole bay area, reference soil representing atmospheric impact, and fish, shellfish and crab commonly consumed as food. The range of concentrations were comparable to or higher than those in other parts of Japan. The origins of these compounds in the catchment area of the bay were investigated in terms of homolog and isomeric compositions in the sediment samples. Biota-sediment accumulation factors for benthic species declined as the degree of chlorination increased.