Effects of surface nanomorphology on the senescence of periodontal ligament stem cells

OBJECTIVES

The effect of TiO2 nanotube morphology on the differentiation potency of senescent periodontal ligament stem cells was investigated.

METHODS

Two types of titanium sheets with TiO2 nanotube morphology (20V-NT and 70V-NT) were prepared via anodic oxidation at 20 and 70 V separately, and their surface morphology was observed. Young periodontal ligament stem cells were cultivated in an osteogenic induction medium, and the most effective surface morphology in promoting osteogenic differentiation was selected. RO3306 and Nutlin-3a were used to induce the aging of young periodontal ligament stem cells, and senescent periodontal ligament stem cells were obtained. The osteogenic differentiation of senescent periodontal ligament stem cells was induced, and the effect of surface morphology on osteogenic differentiation was observed.

RESULTS

Nanotube morphology was achieved on the surfaces of titanium sheets through anodic oxidation, and the diameters of the nanotubes increased with voltage. A significant difference in the effect of nanotube morphology was found among nanotubes with different diameters in the young periodontal ligament stem cells. The surface nanotube morphology of 20V-NT had a more significant effect that promoted osteogenic differentiation. Compared with a smooth titanium sheet, the surface nanotube morphology of 20V-NT increased the number of alkaline phosphatase-positive senescent periodontal ligament stem cells and promoted calcium deposition and the expression of osteogenic marker genes Runt-related transcription factor 2, osteopontin, and osteocalcin.

CONCLUSIONS

A special nanotube morphology enhances the differentiation ability of senescent periodontal ligament stem cells, provides an effective method for periodontal regeneration, and further improves the performance of implants.

Hepatoprotective effects of leaf extract of Annona senegalensis against aflatoxin B1 toxicity in rats

Global aflatoxin contamination of agricultural commodities is of the most concern in food safety and quality. This study investigated the hepatoprotective effect of 80% methanolic leaf extract of Annona senegalensis against aflatoxin B1 (AFB1)-induced toxicity in rats. A. senegalensis has shown to inhibit genotoxicity of aflatoxin B1 in vitro. The rats were divided into six groups including untreated control, aflatoxin B1 only (negative control); curcumin (positive control; 10 mg/kg); and three groups receiving different doses (100 mg/kg, 200 mg/kg, and 300 mg/kg) of A. senegalensis extract. The rats received treatment (with the exception of untreated group) for 7 days prior to intoxication with aflatoxin B1. Serum levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, and creatinine were measured. Hepatic tissues were analysed for histological alterations. Administration of A. senegalensis extract demonstrated hepatoprotective effects against aflatoxin B1-induced toxicity in vivo by significantly reducing the level of serum aspartate aminotransferase and alanine aminotransferase and regenerating the hepatocytes. No significant changes were observed in the levels of alkaline phosphatase, lactate dehydrogenase, and creatinine for the AFB1 intoxicated group, curcumin+AFB1 and Annona senegalensis leaf extract (ASLE)+AFB1 (100 mg/kg, 200 mg/kg, and 300 mg/kg body weight [b.w.]) treated groups. Annona senegalensis is a good candidate for hepatoprotective agents and thus its use in traditional medicine may at least in part be justified.Contribution: The plant extract investigated in this study can be used in animal health to protect the organism from toxicity caused by mycotoxins.

In Vitro and In Vivo Bone-Forming Effect of a Low-Molecular-Weight Collagen Peptide

This study reveals that low-molecular-weight collagen peptide (LMWCP) can stimulate the differentiation and the mineralization of MC3T3-E1 cells in vitro and attenuate the bone remodeling process in ovariectomized (OVX) Sprague-Dawley rats in vivo. Moreover, the assessed LMWCP increased the activity of alkaline phosphatase (ALP), synthesis of collagen, and mineralization in MC3T3-E1 cells. Additionally, mRNA levels of bone metabolism-related factors such as the collagen type I alpha 1 chain, osteocalcin (OCN), osterix, bone sialoprotein, and the Runt family-associated transcription factor 2 were increased in cells treated with 1,000 μg/ml of LMWCP. Furthermore, we demonstrated that critical bone morphometric parameters exhibited significant differences between the LMWCP (400 mg/kg)-receiving and vehicle-treated rat groups. Moreover, the expression of type I collagen and the activity of ALP were found to be higher in both the femur and lumbar vertebrae of OVX rats treated with LMWCP. Finally, the administration of LMWCP managed to alleviate osteogenic parameters such as the ALP activity and the levels of the bone alkaline phosphatase, the OCN, and the procollagen type 1 N-terminal propeptide in OVX rats. Thus, our findings suggest that LMWCP is a promising candidate for the development of food-based prevention strategies against osteoporosis.

Level function levels and oxidative stress markers in patients with multidrug-resistant tuberculosis in the Brazilian Amazon

This study aimed to correlate the values of liver markers with oxidative stress markers in patients with multidrug-resistant tuberculosis in the Brazilian Amazon. A total of 30 patients from the Tuberculosis clinic of a referral hospital were admitted to the study. Whole blood samples were collected for analysis of liver enzyme values and oxidative stress markers by spectrophotometry. The prevalence was male (60%) and the 18-29 age group was the most affected. Patients with multidrug-resistant tuberculosis presented catalase values with a median equal to 6.94 U/gHb and for glutathione, the median was equal to 14.76 µg∕ml. As for the values of liver enzymes (AST, ALT, Gamma-GT and Alkaline phosphatase) the patients had medians equal to 60.50 (U/L); 80 (U/L); 54 (U/L); and 100 (U/L) respectively (p<0.0001). The results suggest a hepatotoxic effect of the drug, which recommends further studies with a larger number of samples in order to investigate the predictors of liver damage in patients with multidrug-resistant tuberculosis.

Alkaline phosphatase LapA regulates quorum sensing-mediated virulence and biofilm formation in Pseudomonas aeruginosa PAO1 under phosphate depletion stress

IMPORTANCE

Our previous study demonstrated that the expression of lapA was induced under phosphate depletion conditions, but its roles in virulence and biofilm formation by Pseudomonas aeruginosa remain largely unknown. This study presents a systematic investigation of the roles of lapA in virulence induction and biofilm formation by constructing a lapA-deficient strain with P. aeruginosa PAO1. The results showed that deletion of the lapA gene evidently reduced elastase activity, swimming motility, C4-HSL, and 3-oxo-C12-HSL production, and increased rhamnolipid production under phosphate depletion stress. Moreover, lapA gene deletion inhibited PAO1 biofilm formation in porcine skin explants by reducing the expression levels of las and rhl quorum sensing systems and extracellular polymeric substance synthesis. Finally, lapA gene deletion also reduced the virulence of PAO1 in Caenorhabditis elegans in fast-kill and slow-kill infection assays. This study provides insights into the roles of lapA in modulating P. aeruginosa virulence and biofilm formation under phosphate depletion stress.

Gymnemic acid-conjugated gelatin scaffold for enhanced bone regeneration: A novel insight to tissue engineering

Bone tissue engineering deals with the design of bone scaffolds. The selection of porous scaffold for osteoblast attachment and suppression of microbial infections are the major challenges that were addressed by designing gelatin scaffolds conjugated with gymnemic acid. Gelatin scaffold was prepared by loading gymnemic acid and morphological characterization, porosity, water absorption behavior, and biocompatibility of the scaffold were studied. The scaffold was introduced to the rat calvarial bone defect (BD) and analyzed the serum C reactive protein, alkaline phosphatase activity, and histology for 1 month to study the reconstruction. Adult Sprague-Dawley rats were used as sham operated control, animal with BD, and animal with BD which was implanted with scaffold (BDMB). The scanning electron micrograph revealed porous nature of scaffold. There was no significant difference in water absorption ability of scaffold. The C reactive protein was not observed in the serum collected on the 5th day postsurgery, supported the biocompatibility. The alkaline phosphatase activity in BDMB was increased when compared with BD on 15th and 20th day and then decreased. New bone tissue formation was detected with hematoxylin-eosin staining. The scaffold is effective in enhancing bone regeneration, which will have therapeutic significance in orthopedics and dentistry.

Increased PHOSPHO1 and alkaline phosphatase expression during the anabolic bone response to intermittent parathyroid hormone delivery

The administration of intermittent parathyroid hormone (iPTH) is anabolic to the skeleton. Recent studies with cultured osteoblasts have revealed that the expression of PHOSPHO1, a bone-specific phosphatase essential for the initiation of mineralisation, is regulated by PTH. Therefore, this study sought to determine whether the bone anabolic response to iPTH involves modulation of expression of Phospho1 and of other enzymes critical for bone matrix mineralisation. To mimic iPTH treatment, primary murine osteoblasts were challenged with 50 nM PTH for 6 h in every 48 h period for 8 days (4 cycles), 14 days (7 cycles) and 20 days (10 cycles) in total. The expression of both Phospho1 and Smpd3 was almost completely inhibited after 4 cycles, whereas 10 cycles were required to stimulate a similar response in Alpl expression. To explore the in vivo role of PHOSPHO1 in PTH-mediated osteogenesis, the effects of 14- and 28-day iPTH (80 µg/kg/day) administration was assessed in male wild-type (WT) and Phospho1-/- mice. The expression of Phospho1, Alpl, Smpd3, Enpp1, Runx2 and Trps1 expression was enhanced in the femora of WT mice following iPTH administration but remained unchanged in the femora of Phospho1-/- mice. After 28 days of iPTH administration, the anabolic response in the femora of WT was greater than that noted in Phospho1-/- mice. Specifically, cortical and trabecular bone volume/total volume, as well as cortical thickness, were increased in femora of iPTH-treated WT but not in iPTH-treated Phospho1-/- mice. Trabecular bone osteoblast number was also increased in iPTH-treated WT mice but not in iPTH-treated Phospho1-/-  mice. The increased levels of Phospho1, Alpl, Enpp1 and Smpd3 in WT mice in response to iPTH administration is consistent with their contribution to the potent anabolic properties of iPTH in bone. Furthermore, as the anabolic response to iPTH was attenuated in mice deficient in PHOSPHO1, this suggests that the osteoanabolic effects of iPTH are at least partly mediated via bone mineralisation processes.

The effect of Favipiravir on liver enzyme among patients with mild to moderate COVID-19 infection: A prospective cohort study

Teratogenicity and hyperuricemia are considered as the major adverse effects of favipiravir, but less is known about other possible side effects which includes drug-induced liver damage and renal injury. In the current research, assessment of favipiravir-induced liver injury was performed by evaluating liver enzymes among patients with mild to moderate COVID-19 infection. A prospective cohort study was conducted on 66 patients diagnosed with mild to moderate COVID-19 infection who were treated with favipiravir for 5 days. During this period, a baseline assessment of liver enzymes (aspartate aminotransferase - AST, alanine transaminase - ALT and alkaline phosphatase - ALP) in addition to bilirubin before initiation of therapy and after 1 day of completion of therapy were carried out. The comparison of all measured parameters among all patients before and after receiving the treatment showed that non-significant differences were obtained in their levels. It was noticed that COVID-19 patients demonstrated high AST levels in which only 16 patients out of the all-subjected cases (66 patients) had AST levels of less than 45 U/L whereas the majority of patients showed normal ALT, ALP, and bilirubin levels. It was concluded that 5 days administration of favipiravir in mild to moderate COVID-19 patients who had no previous liver diseases did not affect the liver enzymes significantly and only transient elevations were occurred.

circRNA422 enhanced osteogenic differentiation of bone marrow mesenchymal stem cells during early osseointegration through the SP7/LRP5 axis

Circular RNAs (circRNAs) play an important role in biological activities, especially in regulating osteogenic differentiation of stem cells. However, no studies have reported the role of circRNAs in early osseointegration. Here we identified a new circRNA, circRNA422, from rat bone marrow mesenchymal stem cells (BMSCs) cultured on sandblasted, large-grit, acid-etched titanium surfaces. The results showed that circRNA422 significantly enhanced osteogenic differentiation of BMSCs with increased expression levels of alkaline phosphatase, the SP7 transcription factor (SP7/osterix), and lipoprotein receptor-related protein 5 (LRP5). Silencing of circRNA422 had opposite effects. There were two SP7 binding sites on the LRP5 promoter, indicating a direct regulatory relationship between SP7 and LRP5. circRNA422 could regulate early osseointegration in in vivo experiments. These findings revealed an important function of circRNA422 during early osseointegration. Therefore, circRNA422 may be a potential therapeutic target for enhancing implant osseointegration.

Antibacterial activity and mechanism of ginger extract against Ralstonia solanacearum

AIMS

The current study aimed to determine the chemical compositions of ginger extract (GE) and to assess the antibacterial activities of GE against the ginger bacterial wilt pathogen Ralstonia solanacearum and to screen their mechanisms of action.

METHODS AND RESULTS

A total of 393 compounds were identified by using ultra-performance liquid chromatography and tandem-mass spectrometry. The antibacterial test indicated that GE had strong antibacterial activity against R. solanacearum and that the bactericidal effect exhibited a dose-dependent manner. The minimum inhibitory concentration and minimum bactericidal concentration of R. solanacearum were 3.91 and 125 mg/ml, respectively. The cell membrane permeability and integrity of R. solanacearum were destroyed by GE, resulting in cell content leakage, such as electrolytes, nucleic acids, proteins, extracellular adenosine triphosphate and exopoly saccharides. In addition, the activity of cellular succinate dehydrogenase and alkaline phosphatase of R. solanacearum decreased gradually with an increase in the GE concentration. Scanning electron microscopy analysis revealed that GE treatment changed the morphology of the R. solanacearum cells. Further experiments demonstrated that GE delayed or slowed the occurrence of bacterial wilt on ginger.

CONCLUSIONS

GE has a significant antibacterial effect on R. solanacearum, and the antibacterial effect is concentration dependent. The GE treatments changed the morphology, destroyed membrane permeability and integrity, reduced key enzyme activity and inhibit the synthesis of the virulence factor EPS of R. solanacearum. GE significantly controlled the bacterial wilt of ginger during infection.

SIGNIFICANCE AND IMPACT OF THE STUDY

This research provides insight into the antimicrobial mechanism of GE against R. solanacearum, which will open a new application field for GE.

Prophylactic role of olive fruit extract against cigarette smoke-induced oxidative stress in Sprague-Dawley rats

Cigarette smoke exposure increases the production of free radicals leading to initiation of several pathological conditions by triggering the oxidative stress and inflammatory cascade. Olive fruit owing to its unique phytochemical composition possesses antioxidant, immune modulatory, and anti-inflammatory potential. Considering the compositional alterations in olive fruits during ripening, the current experimental trail was designed to investigate the prophylactic role of green and black olives against the oxidative stress induced by cigarette smoke exposure in rats. Purposely, rats were divided into five different groups: NC (negative control; normal diet), PC [positive control; normal diet + smoke exposure (SE)], drug (normal diet + SE + citalopram), GO (normal diet + SE + green olive extract), and BO (normal diet + SE + black olive extract). Rats of all groups were exposed to cigarette smoke except "NC" and were sacrificed for collection of blood and organs after 28 days of experimental trial. The percent reduction in total oxidative stress by citalopram and green and black olive extracts in serum was 29.72, 58.69, and 57.97%, respectively, while the total antioxidant capacity increased by 30.78, 53.94, and 43.98%, accordingly in comparison to PC. Moreover, malondialdehyde (MDA) was reduced by 29.63, 42.59, and 45.70% in drug, GO, and BO groups, respectively. Likewise, green and black olive extracts reduced the leakage of hepatic enzymes in sera, alkaline phosphatase (ALP) by 23.44 and 25.80% and 35.62 and 37.61%, alanine transaminase (ALT) by 42.68 and 24.39% and 51.04 and 35.41%, and aspartate transaminase (AST) by 31.51 and 16.07% and 40.50 and 27.09% from PC and drug group, respectively. Additionally, olive extracts also maintained the antioxidant pool, i.e., superoxide dismutase, catalase, and glutathione in serum. Furthermore, histological examination revealed that olive extracts prevented the cigarette smoke-induced necrosis, pyknotic alterations, and congestion in the lung, hepatic, and renal parenchyma. Besides, gene expression analysis revealed that olive extracts and citalopram decreased the brain and lung damage caused by stress-induced upregulation of NRF-2 and MAPK signaling pathways. Hence, it can be concluded that olives (both green and black) can act as promising antioxidant in alleviating the cigarette smoke-induced oxidative stress.

Meta-Analysis of Effects of Nutritional Intervention Combined with Calcium Carbonate D3 Tablets on Bone Mineral Density, Bone Metabolism, and Curative Effect in Patients with Osteoporosis

To investigate the changes in bone mineral density, bone metabolism, and efficacy of nutritional intervention combined with calcium carbonate D3 tablets in patients with osteoporosis, a RevMan 5.2 software meta-analysis was conducted in this study. According to the therapeutic direction of nutritional intervention combined with calcium carbonate D3 tablets for osteoporosis patients, relevant literature were searched in Wanfang Medical, CNKI, VIP, and PubMed literature databases at home and abroad. Keywords included bone mineral density, bone metabolism, blood calcium (Ca), blood phosphorus (P), osteocalcin (OC), bone mineral density (BMD), serum alkaline phosphatase (ALP), efficacy, osteoporosis, and nutritional intervention. Literature that met the criteria were deleted, and meta-analysis was performed using RevMan 5.2 software. The results indicate that a total of 10 Chinese literature were included. Compared with the monotherapy group, the clinical efficacy, osteocalcin, BMD, alkaline phosphatase, calcium, and phosphorus were significantly higher in the combination group (P < 0.05). Based on calcium carbonate D3, treatment combined with nutritional intervention can enhance the clinical efficacy, bone metabolism, and bone mineral density of patients with osteoporosis, and nutritional intervention combined with calcium carbonate D3 tablets is a feasible program to promote the recovery of patients with osteoporosis.

Protease-activated receptor-2 dependent and independent responses of bone cells to prostate cancer cell secretory products

BACKGROUND

Metastatic prostate cancer lesions in the skeleton are frequently characterized by excessive formation of bone. Prostate cancer cells secrete factors, including serine proteases, that are capable of influencing the behavior of surrounding cells. Some of these proteases activate protease-activated receptor-2 (PAR₂ ), which is expressed by osteoblasts (bone-forming cells) and precursors of osteoclasts (bone-resorbing cells). The aim of the current study was to investigate a possible role for PAR₂ in regulating the behavior of bone cells exposed to metastatic prostate cancer cells.

METHODS

The effect of medium conditioned by the PC3, DU145, and MDA-PCa-2b prostate cancer cell lines was investigated in assays of bone cell function using cells isolated from wildtype and PAR₂ -null mice. Osteoclast differentiation was assessed by counting tartrate-resistant acid phosphatase-positive multinucleate cells in bone marrow cultured in osteoclastogenic medium. Osteoblasts were isolated from calvariae of neonatal mice, and BrdU incorporation was used to assess their proliferation. Assays of alkaline phosphatase activity and quantitative PCR analysis of osteoblastic gene expression were used to assess osteoblast differentiation. Responses of osteoblasts to medium conditioned by MDA-PCa-2b cells were analyzed by RNAseq.

RESULTS

Conditioned medium (CM) from all three cell lines inhibited osteoclast differentiation independently of PAR₂ . Media from PC3 and DU145 cells had no effect on assays of osteoblast function. Medium conditioned by MDA-PCa-2b cells stimulated BrdU incorporation in both wildtype and PAR₂ -null osteoblasts but increased alkaline phosphatase activity and Runx2 and Col1a1 expression in wildtype but not PAR₂ -null cells. Functional enrichment analysis of RNAseq data identified enrichment of multiple gene ontology terms associated with lysosomal function in both wildtype and PAR₂ -null cells in response to MDA-PCa-2b-CM. Analysis of individual genes identified osteogenesis-associated genes that were either upregulated by MDA-PCa-2b-CM selectively in wildtype cells or downregulated selectively in PAR₂ -null cells.

CONCLUSIONS

Factors secreted by prostate cancer cells influence bone cell behavior through both PAR₂ -dependent and -independent mechanisms. Both PAR₂ -independent suppression of osteoclast differentiation and PAR₂ -dependent stimulation of osteogenesis are likely to determine the nature of prostate cancer metastases in bone.

Investigation of Hematological and Biochemical Effects of Feeding Date in the Early Morning on Empty Stomach vs. after Nutrition on Rabbits

Date seeds have been studied for their possible health advantages as they are employed in various traditional remedies. This study aimed to investigate how date affected hematology, renal, and liver function in rabbits before and after date feeding. In total, 30 rabbits were used in this investigation, and they were divided into two groups (n=15). Group one (G1) was considered the control group and received only a meal without dates for 30 days, and group two (G2) was given date seed extract a about 30 ml/kg b.w. for 30 days. The findings revealed that daily oral administration of date extract resulted in a considerable increase in hemoglobin (Hgb) concentration. It is now recognized as a useful source of natural therapeutic ingredients for a variety of ailments. The study results showed that the oral administration of dates led to a significant increase in Hgb concentration, Hgb indices (MCH, MCV, MCHC, PLT, WBCs, and RBCs) and a significant increase in total protein, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, creatinine, and blood urea nitrogen levels (P≤0.05). However, there were no significant changes in albumin in G2, compared to G1. Finally, dates may help to increase biochemical and hematological parameters in rabbits.

Barbaloin Promotes Osteogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells: Involvement of Wnt/β-catenin Signaling Pathway

BACKGROUND

Barbaloin, found in Aloe vera, exerts broad pharmacological activities, including antioxidant, anti-inflammatory, and anti-cancer. This study aims to investigate the effects of barbaloin on the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs).

METHODS

Osteogenic induction of hBMSCs was performed in the presence or absence of barbaloin. Cell viability was determined by using the CCK-8 assay. The characteristic of hBMSCs was identified by using flow cytometry. Intracellular alkaline phosphatase (ALP) staining was performed to evaluate the ALP activity in hBMSCs. Alizarin Red S staining was performed to evaluate the matrix mineralization. The mRNA and protein levels of target genes were determined using qRT-PCR and western blotting, respectively.

RESULTS

Treatment with barbaloin (10 and 20 μg/mL) significantly increased cell viability of hBMSCs after 72 hours. In addition, treatment with barbaloin increased the mRNA expression levels of ALP and its activities. Treatment with barbaloin also increased matrix mineralization and the mRNA and protein levels of late-differentiated osteoblast marker genes BMP2, RUNX2, and SP7 in hBMSCs. The underlying mechanisms revealed that barbaloin increased the protein expressions of Wnt/β-catenin pathway-related biomarkers.

CONCLUSION

Barbaloin promotes osteogenic differentiation of hBMSCs by the regulation of the Wnt/β-catenin signaling pathway.

Intestinal alkaline phosphatase targets the gut barrier to prevent aging

Gut barrier dysfunction and gut-derived chronic inflammation play crucial roles in human aging. The gut brush border enzyme intestinal alkaline phosphatase (IAP) functions to inhibit inflammatory mediators and also appears to be an important positive regulator of gut barrier function and microbial homeostasis. We hypothesized that this enzyme could play a critical role in regulating the aging process. We tested the role of several IAP functions for prevention of age-dependent alterations in intestinal homeostasis by employing different loss-of-function and supplementation approaches. In mice, there is an age-related increase in gut permeability that is accompanied by increases in gut-derived portal venous and systemic inflammation. All these phenotypes were significantly more pronounced in IAP-deficient animals. Oral IAP supplementation significantly decreased age-related gut permeability and gut-derived systemic inflammation, resulted in less frailty, and extended lifespan. Furthermore, IAP supplementation was associated with preserving the homeostasis of gut microbiota during aging. These effects of IAP were also evident in a second model system, Drosophilae melanogaster. IAP appears to preserve intestinal homeostasis in aging by targeting crucial intestinal alterations, including gut barrier dysfunction, dysbiosis, and endotoxemia. Oral IAP supplementation may represent a novel therapy to counteract the chronic inflammatory state leading to frailty and age-related diseases in humans.

Effect of alkaline phosphatase on sepsis-associated acute kidney injury patients: A systematic review and meta-analysis

BACKGROUND

This systematic review and meta-analysis were performed to evaluate kidney function in patients with sepsis-associated acute kidney injury (SA-AKI) on alkaline phosphatase (AP) therapy.

METHODS

PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched electronically from inception until May 4, 2019 and randomized controlled studies assessing AP treatment in patients with SA-AKI were included. Pool analyses with fixed effects or random effects models calculated pooled mean, standard deviation, and odds ratio (OR) with 95% confidence interval (CI).

RESULTS

Four randomized controlled trials involving AP therapy for 392 patients with SA-AKI were included. AP had a positive effect on endogenous creatinine clearance (ECC) in patients with SA-AKI at day 14 (random effects: mean difference = 10.56, 95% CI = 2.27-18.84, P = .01) and day 28 (random effects: mean difference = 14.30, 95% CI = 6.27-22.33, P = .0005). All-cause mortality at day 28 (fixed effects: OR = 0.62, 95% CI = 0.40-0.97, P = .04) and day 90 (fixed effects: OR = 0.61, 95% CI = 0.39-0.96, P = .03) improved. Plasma creatinine level (fixed effects: mean difference = -76.83, 95% CI = -146.92 to -6.74, P = .03) and biomarkers level (random effects: mean difference = -6.57, 95% CI = -10.74 to -2.40, P < .00001) also improved in the therapy group compared with placebo.

CONCLUSION

In patients with SA-AKI, AP showed a relatively late protective effect by improving ECC at days 7, 14, and 28. ECC level improved when patients received AP dose of 0.212 mg/kg. Mortality improved at days 28 and 90, respectively, when patients received AP dose of 1.6 mg/kg. Levels of overall AKI biomarkers were improved in short term.

Recovery of bone mineralization and quality during asfotase alfa treatment in an adult patient with infantile-onset hypophosphatasia

Hypophosphatasia (HPP) is a hereditary musculoskeletal disorder characterized by low serum alkaline phosphatase (ALP) activity leading to poor bone mineralization. On a micro-morphological level, this may not only be reflected by an enrichment of osteoid but also a degradation of bone quality. Asfotase alfa is an enzyme replacement therapy that was recently demonstrated to improve bone mineralization as well as clinical status (e.g. growth, muscle strength and quality of life). However, the underlying changes of bone quality parameters on asfotase alfa treatment are currently not known. In the present study, we report a 24-year-old woman with genetically confirmed infantile-onset HPP and recurrent fractures. While the initiated asfotase alfa treatment was followed by rapid clinical improvements (i.e., disappearance of bone marrow edema, increase of muscle strength), the BMD assessed by DXA at the hip and spine increased moderately at two years follow-up. A detailed skeletal assessment using high-resolution peripheral quantitative computed tomography (HR-pQCT) and a high-resolution analysis of two consecutive iliac crest bone biopsies revealed only minor improvements of bone microarchitecture but a remarkable reduction of osteoid parameters. Furthermore, the high mineralization heterogeneity at baseline assessed by quantitative backscattered electron imaging (qBEI) decreased after 2 year of asfotase alfa treatment. Finally, we found an increase in mineral maturation reflected by higher mineral-to-matrix and carbonate-to-phosphate ratios using Fourier transform infrared spectroscopy (FTIR) imaging as well as increased local mechanical properties using reference point indentation (RPI). Taken together, our findings provide evidence for an improvement of bone quality indices beyond the mere reduction of osteoid indices and thereby contribute to the understanding of fracture risk reduction in HPP patients on asfotase alfa treatment.

Effect of Human Recombinant Alkaline Phosphatase on 7-Day Creatinine Clearance in Patients With Sepsis-Associated Acute Kidney Injury: A Randomized Clinical Trial

IMPORTANCE

Sepsis-associated acute kidney injury (AKI) adversely affects long-term kidney outcomes and survival. Administration of the detoxifying enzyme alkaline phosphatase may improve kidney function and survival.

OBJECTIVE

To determine the optimal therapeutic dose, effect on kidney function, and adverse effects of a human recombinant alkaline phosphatase in patients who are critically ill with sepsis-associated AKI.

DESIGN, SETTING, AND PARTICIPANTS

The STOP-AKI trial was an international (53 recruiting sites), randomized, double-blind, placebo-controlled, dose-finding, adaptive phase 2a/2b study in 301 adult patients admitted to the intensive care unit with a diagnosis of sepsis and AKI. Patients were enrolled between December 2014 and May 2017, and follow-up was conducted for 90 days. The final date of follow-up was August 14, 2017.

INTERVENTIONS

In the intention-to-treat analysis, in part 1 of the trial, patients were randomized to receive recombinant alkaline phosphatase in a dosage of 0.4 mg/kg (n = 31), 0.8 mg/kg (n = 32), or 1.6 mg/kg (n = 29) or placebo (n = 30), once daily for 3 days, to establish the optimal dose. The optimal dose was identified as 1.6 mg/kg based on modeling approaches and adverse events. In part 2, 1.6 mg/kg (n = 82) was compared with placebo (n = 86).

MAIN OUTCOMES AND MEASURES

The primary end point was the time-corrected area under the curve of the endogenous creatinine clearance for days 1 through 7, divided by 7 to provide a mean daily creatinine clearance (AUC1-7 ECC). Incidence of fatal and nonfatal (serious) adverse events ([S]AEs) was also determined.

RESULTS

Overall, 301 patients were enrolled (men, 70.7%; median age, 67 years [interquartile range {IQR}, 59-73]). From day 1 to day 7, median ECC increased from 26.0 mL/min (IQR, 8.8 to 59.5) to 65.4 mL/min (IQR, 26.7 to 115.4) in the recombinant alkaline phosphatase 1.6-mg/kg group vs from 35.9 mL/min (IQR, 12.2 to 82.9) to 61.9 mL/min (IQR, 22.7 to 115.2) in the placebo group (absolute difference, 9.5 mL/min [95% CI, -23.9 to 25.5]; P = .47). Fatal adverse events occurred in 26.3% of patients in the 0.4-mg/kg recombinant alkaline phosphatase group; 17.1% in the 0.8-mg/kg group, 17.4% in the 1.6-mg/kg group, and 29.5% in the placebo group. Rates of nonfatal SAEs were 21.0% for the 0.4-mg/kg recombinant alkaline phosphatase group, 14.3% for the 0.8-mg/kg group, 25.7% for the 1.6-mg/kg group, and 20.5% for the placebo group.

CONCLUSIONS AND RELEVANCE

Among patients who were critically ill with sepsis-associated acute kidney injury, human recombinant alkaline phosphatase compared with placebo did not significantly improve short-term kidney function. Further research is necessary to assess other clinical outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02182440.

Alkaline Phosphatase, Soluble Extracellular Adenine Nucleotides, and Adenosine Production after Infant Cardiopulmonary Bypass

Rationale

Decreased alkaline phosphatase activity after infant cardiac surgery is associated with increased post-operative cardiovascular support requirements. In adults undergoing coronary artery bypass grafting, alkaline phosphatase infusion may reduce inflammation. Mechanisms underlying these effects have not been explored but may include decreased conversion of extracellular adenine nucleotides to adenosine.

Objectives

1) Evaluate the association between alkaline phosphatase activity and serum conversion of adenosine monophosphate to adenosine after infant cardiac surgery; 2) assess if inhibition/supplementation of serum alkaline phosphatase modulates this conversion.

Methods and Research

Pre/post-bypass serum samples were obtained from 75 infants <4 months of age. Serum conversion of 13C5-adenosine monophosphate to 13C5-adenosine was assessed with/without selective inhibition of alkaline phosphatase and CD73. Low and high concentration 13C5-adenosine monophosphate (simulating normal/stress concentrations) were used. Effects of alkaline phosphatase supplementation on adenosine monophosphate clearance were also assessed. Changes in serum alkaline phosphatase activity were strongly correlated with changes in 13C5-adenosine production with or without CD73 inhibition (r = 0.83; p<0.0001). Serum with low alkaline phosphatase activity (≤80 U/L) generated significantly less 13C5-adenosine, particularly in the presence of high concentration 13C5-adenosine monophosphate (10.4μmol/L vs 12.9μmol/L; p = 0.0004). Inhibition of alkaline phosphatase led to a marked decrease in 13C5-adenosine production (11.9μmol/L vs 2.7μmol/L; p<0.0001). Supplementation with physiologic dose human tissue non-specific alkaline phosphatase or high dose bovine intestinal alkaline phosphatase doubled 13C5-adenosine monophosphate conversion to 13C5-adenosine (p<0.0001).

Conclusions

Alkaline phosphatase represents the primary serum ectonucleotidase after infant cardiac surgery and low post-operative alkaline phosphatase activity leads to impaired capacity to clear adenosine monophosphate. AP supplementation improves serum clearance of adenosine monophosphate to adenosine. These findings represent a potential therapeutic mechanism for alkaline phosphatase infusion during cardiac surgery.

New and Noteworthy

We identify alkaline phosphatase (AP) as the primary soluble ectonucleotidase in infants undergoing cardiopulmonary bypass and show decreased capacity to clear AMP when AP activity decreases post-bypass. Supplementation of AP ex vivo improves this capacity and may represent the beneficial therapeutic mechanism of AP infusion seen in phase 2 studies.

Enrichment of thermosensitive chitosan hydrogels with glycerol and alkaline phosphatase for bone tissue engineering applications

Thermosensitive injectable chitosan hydrogels can be formed by neutralization of acidic chitosan solutions with sodium betaglycerophosphate (Na-β-GP) coupled with increasing temperature to body temperature. Such hydrogels have been considered for applications in bone regeneration. In this study, chitosan hydrogels were enriched with glycerol and the enzyme alkaline phosphatase (ALP) with a view to improving their suitability as materials for bone tissue engineering. Mineral formation was confirmed by infrared spectroscopy (FTIR) and increases in the mass fraction of the hydrogel not consisting of water. Incorporation of ALP in hydrogels followed by incubation in a solution containing calcium ions and glycerophosphate, a substrate for ALP, led to formation of calcium phosphate within the hydrogel. MG-63 osteoblast-like cells were cultivated in eluates from hydrogels containing ALP and without ALP at different dilutions and directly on the hydrogel samples. Hydrogels containing ALP exhibited superior cytocompatibility to ALP-free hydrogels. These results pave the way for the use of glycerol- and ALP-enriched hydrogels in bone regeneration.

Enhanced Bacterial α(2,6)-Sialyltransferase Reaction through an Inhibition of Its Inherent Sialidase Activity by Dephosphorylation of Cytidine-5'-Monophosphate

Bacterial α(2,6)-sialyltransferases (STs) from Photobacterium damsela, Photobacterium sp. JT-ISH-224, and P. leiognathi JT-SHIZ-145 were recombinantly expressed in Escherichia coli and their ST activities were compared directly using a galactosylated bi-antennary N-glycan as an acceptor substrate. In all ST reactions, there was an increase of sialylated glycans at shorter reaction times and later a decrease in prolonged reactions, which is related with the inherent sialidase activities of bacterial STs. These sialidase activities are greatly increased by free cytidine monophosphate (CMP) generated from a donor substrate CMP-N-acetylneuraminic acid (CMP-Neu5Ac) during the ST reactions. The decrease of sialylated glycans in prolonged ST reaction was prevented through an inhibition of sialidase activity by simple treatment of alkaline phosphatase (AP), which dephosphorylates CMP to cytidine. Through supplemental additions of AP and CMP-Neu5Ac to the reaction using the recombinant α(2,6)-ST from P. leiognathi JT-SHIZ-145 (P145-ST), the content of bi-sialylated N-glycan increased up to ~98% without any decrease in prolonged reactions. This optimized P145-ST reaction was applied successfully for α(2,6)-sialylation of asialofetuin, and this resulted in a large increase in the populations of multi-sialylated N-glycans compared with the reaction without addition of AP and CMP-Neu5Ac. These results suggest that the optimized reaction using the recombinant P145-ST readily expressed from E. coli has a promise for economic glycan synthesis and glyco-conjugate remodeling.

Enzyme replacement therapy on hypophosphatasia mouse model

Hypophosphatasia (HPP) is an inborn error of metabolism caused by deficiency of the tissue-nonspecific alkaline phosphatase (TNSALP), resulting in a defect of bone mineralization. Natural substrates for this ectoenzyme accumulate extracellulary including inorganic pyrophosphate (PPi), an inhibitor of mineralization, and pyridoxal 5-phosphate (PLP), a co-factor form of vitamin B6. Enzyme replacement therapy (ERT) for HPP by functional TNSALP is one of the therapeutic options. The C-terminal-anchorless human recombinant TNSALP derived from Chinese hamster ovary cell lines was purified. TNSALP-null mice (Akp2 (-/-) ), an infantile model of HPP, were treated from birth using TNSALP and vitamin B6 diet. Long-term efficacy studies of ERT consisted of every 3 days subcutaneous or intravenous injections till 28 days old (dose 20 U/g) and subsequently every 3 days intravenous injections for 6 months (dose 10 U/g). We assessed therapeutic effect by growth and survival rates, fertility, skeletal manifestations, and radiographic and pathological finding. Treated Akp2 (-/-) mice grew normally till 4 weeks and appeared well with a minimum skeletal abnormality as well as absence of epilepsy, compared with untreated mice which died by 3 weeks old. The prognosis of TNSALP-treated Akp2 (-/-) mice was improved substantially: 1) prolonged life span over 6 months, 2) improvement of the growth, and 3) normal fertility. After 6 months of treatment, we found moderate hypomineralization with abnormal proliferative chondrocytes in growth plate and articular cartilage. In conclusion, ERT with human native TNSALP improves substantial clinical manifestations in Akp2 (-/-) mice, suggesting that ERT with anchorless TNSALP is also a potential therapy for HPP.

Intestinal alkaline phosphatase prevents metabolic syndrome in mice

Metabolic syndrome comprises a cluster of related disorders that includes obesity, glucose intolerance, insulin resistance, dyslipidemia, and fatty liver. Recently, gut-derived chronic endotoxemia has been identified as a primary mediator for triggering the low-grade inflammation responsible for the development of metabolic syndrome. In the present study we examined the role of the small intestinal brush-border enzyme, intestinal alkaline phosphatase (IAP), in preventing a high-fat-diet-induced metabolic syndrome in mice. We found that both endogenous and orally supplemented IAP inhibits absorption of endotoxin (lipopolysaccharides) that occurs with dietary fat, and oral IAP supplementation prevents as well as reverses metabolic syndrome. Furthermore, IAP supplementation improves the lipid profile in mice fed a standard, low-fat chow diet. These results point to a potentially unique therapy against metabolic syndrome in at-risk humans.

Enzyme-replacement therapy in life-threatening hypophosphatasia

BACKGROUND

Hypophosphatasia results from mutations in the gene for the tissue-nonspecific isozyme of alkaline phosphatase (TNSALP). Inorganic pyrophosphate accumulates extracellularly, leading to rickets or osteomalacia. Severely affected babies often die from respiratory insufficiency due to progressive chest deformity or have persistent bone disease. There is no approved medical therapy. ENB-0040 is a bone-targeted, recombinant human TNSALP that prevents the manifestations of hypophosphatasia in Tnsalp knockout mice.

METHODS

We enrolled infants and young children with life-threatening or debilitating perinatal or infantile hypophosphatasia in a multinational, open-label study of treatment with ENB-0040. The primary objective was the healing of rickets, as assessed by means of radiographic scales. Motor and cognitive development, respiratory function, and safety were evaluated, as well as the pharmacokinetics and pharmacodynamics of ENB-0040.

RESULTS

Of the 11 patients recruited, 10 completed 6 months of therapy; 9 completed 1 year. Healing of rickets at 6 months in 9 patients was accompanied by improvement in developmental milestones and pulmonary function. Elevated plasma levels of the TNSALP substrates inorganic pyrophosphate and pyridoxal 5'-phosphate diminished. Increases in serum parathyroid hormone accompanied skeletal healing, often necessitating dietary calcium supplementation. There was no evidence of hypocalcemia, ectopic calcification, or definite drug-related serious adverse events. Low titers of anti-ENB-0040 antibodies developed in four patients, with no evident clinical, biochemical, or autoimmune abnormalities at 48 weeks of treatment.

CONCLUSIONS

ENB-0040, an enzyme-replacement therapy, was associated with improved findings on skeletal radiographs and improved pulmonary and physical function in infants and young children with life-threatening hypophosphatasia. (Funded by Enobia Pharma and Shriners Hospitals for Children; ClinicalTrials.gov number, NCT00744042.).

Osteoblast function in myeloma

Multiple myeloma (MM) is the most frequent cancer to involve the skeleton and results in purely osteolytic lesions that rarely heal. MM bone disease is responsible for some of the most devastating complications of MM. The marrow microenvironment plays a key role in MM bone disease as well as in the initiation, expansion and chemoresistance of MM cells. How this microenvironment becomes so supportive of MM, and the contribution and interaction of the various components of the microenvironment to enhancing MM growth are only beginning to be understood. However, it is clear that suppression of osteoblast activity plays a key role in the bone destructive process as well as progression of the tumor burden in myeloma. The impairment of osteoblast activity in MM results primarily from blockade of osteogenic differentiation of mesenchymal progenitors to mature osteoblasts. MM patients have low to normal levels of bone formation markers, such as alkaline phosphatase and osteocalcin in the setting of increased bone resorption. In contrast, MM patients without bone lesions display balanced bone remodeling with increased osteoclastogenesis and normal or increased bone formation rates. Both soluble factors and cell-to-cell contact between MM cells and osteoblast progenitors are responsible for the suppression of osteoblast differentiation in MM. In this article, the mechanism responsible for osteoblast suppression will be reviewed, and the effects of novel bone anabolic agents on myeloma bone disease will be discussed.

A chemical phosphorylation-inspired design for Type I collagen biomimetic remineralization

OBJECTIVES

Type I collagen alone cannot initiate tissue mineralization. Sodium trimetaphosphate (STMP) is frequently employed as a chemical phosphorylating reagent in the food industry. This study examined the feasibility of using STMP as a functional analog of matrix phosphoproteins for biomimetic remineralization of resin-bonded dentin.

METHODS

Equilibrium adsorption and desorption studies of STMP were performed using demineralized dentin powder (DDP). Interaction between STMP and DDP was examined using Fourier transform-infrared spectroscopy. Based on those results, a bio-inspired mineralization scheme was developed for chemical phosphorylation of acid-etched dentin with STMP, followed by infiltration of the STMP-treated collagen matrix with two etch-and-rinse adhesives. Resin-dentin interfaces were remineralized in a Portland cement-simulated body fluid system, with or without the use of polyacrylic acid (PAA) as a dual biomimetic analog. Remineralized resin-dentin interfaces were examined unstained using transmission electron microscopy.

RESULTS

Analysis of saturation binding curves revealed the presence of irreversible phosphate group binding sites on the surface of the DDP. FT-IR provided additional evidence of chemical interaction between STMP and DDP, with increased in the peak intensities of the PO and P-O-C stretching modes. Those peaks returned to their original intensities after alkaline phosphatase treatment. Evidence of intrafibrillar apatite formation could be seen in incompletely resin-infiltrated, STMP-phosphorylated collagen matrices only when PAA was present in the SBF.

SIGNIFICANCE

These results reinforce the importance of PAA for sequestration of amorphous calcium phosphate nanoprecursors in the biomimetic remineralization scheme. They also highlight the role of STMP as a templating analog of dentin matrix phosphoproteins for inducing intrafibrillar remineralization of apatite nanocrystals within the collagen matrix of incompletely resin-infiltrated dentin.

[Effects of different titanium-treated surfaces on rat's osteoblast function and cell cycle]

This study is designed to compare the distribution, function and cell cycle of rat osteoblast cultured on sandblasting and acid-alkali base titanium surface versus that cultured on carbonated hydroxyapatite titanium surface; the aim is to probe the influences of different surfaces on the function of osteoblasts. SD rat's osteoblasts were primary-cultured, passaged to the 4th generation and then cultured on the two kinds of surfaces. The cellular modality was observed using an inverted microscopy analyzing system. Proliferation was examined by MTT chromatometry and depicted by growth curve. Expression of alkaline phosphatase (ALP) was detected by Enzyme-Linked Immunosorbent Assay. The cell apoptosis and proliferation were examined by flow cytometry. The proliferation curve and index of the osteoblasts on the two kinds of surfaces were almost the same. However, on the carbonated hydroxyapatite group, the level of alkaline phosphatase expression of osteoblasts was higher and kept longer than the other one. In conclusion, the elements on the titanium surface influence the cell function, and the surface with rich PO4(3-) and Ga2+ can enhance the mineralization function of rat osteoblast.

Fibroblast growth factor 2 requires complex formation with ATP for neuroprotective activity

The neurotrophic and neuroprotective activity of fibroblast growth factor (FGF2) is well documented. In this study, we attempted to demonstrate that binding of ATP to FGF2 is essential for its neuroprotective effect. Incubation of primary cultures of rat embryonic (E18) cortical neurons with alkaline phosphatase decreased the ATP concentration in the culture medium from about 8 to 0.3 nM measured luminometrically. Reduction of ATP concentration below 1 nM abolished the neuroprotective effect of FGF2. However, when the more stable nucleotide triphosphate gammaS-ATP was used which could not be cleaved by alkaline phosphatase, FGF2 still protected the cultured cortical neurons against damage. In control experiments alkaline phosphatase alone did not influence neuroprotection. In addition, also ATPase and apyrase were used as ATP cleaving enzymes. Added to the culture medium, both enzymes were capable of decreasing ATP below the critical level of approximately 1 nM, and the neuroprotective activity of FGF2 was abolished. Thus, our results demonstrate for the first time that the FGF2/ATP complex but not FGF2 alone mediates neuroprotection.

Alkaline phosphatase-polyresorcinol complex: characterization and application to seed coating

An alkaline phosphatase (EC 3.1.3.1) from Escherichia coli ATCC27257 was immobilized by copolymerization with resorcinol. The phosphatase-polyresorcinol complex synthesized retained about 74% of the original enzymatic activity. The pH and temperature profile of the immobilized and free enzyme revealed a similar behavior. Kinetic parameters were determined: K(m) and K(i) values were 2.44 and 0.423 mM, respectively, for the phosphatase-polyresorcinol complex and 1.07 and 0.069 mM, respectively, for free phosphatase. The thermal and storage stabilities of the immobilized phosphatase were higher than those of the native one. On addition to soil, free enzyme was completely inactivated in 4 days, whereas the phosphatase-polyresorcinol complex was comparatively stable. Barley seed coated with the immobilized enzyme exhibited higher rhizosphere phosphatase activity. Under pot culture conditions, an increase in the soil inorganic phosphorus was detected when the seed was encapsulated with the phosphatase-polyresorcinol complex, and a positive influence on biomass and inorganic phosphorus concentration of shoot was observed.

Effect of an isoflavones-containing red clover preparation and alkaline supplementation on bone metabolism in ovariectomized rats

The aim of this study was to test the combined effect of a quality-controlled red clover extract (RCE) standardized to contain 40% isoflavones by weight (genistein, daidzein, biochanin A, and formononetin present as hydrolyzed aglycones) together with a modified alkaline supplementation on bone metabolic and biomechanical parameters in an experimental model of surgically-induced menopause. Sprague-Dawley female rats were maintained under controlled standard conditions of light and fed with conventional food of standard calcium content and no alfalfa or soybean components. Rats were randomized into four groups: Group A represented normal rats (sham operated) while three other groups were ovariectomized (OVX) and fed for three months as follows: standard food (group B), 6 mg/kg/day food mixed with RCE (Group C), or given 6 mg/kg/day of RCE plus a modified alkaline supplementation (BP) through a nasogastric tube at a dose of 16 mg (group D). The animals were killed 90 days after surgery. As compared to group B, RCE or RCE + BP treatments brought about significantly higher level of estradiol and mitigated the weight loss of the uterus and improved maximum load of the femoral neck. Osteocalcin level showed an over 65% increase in group B but both RCE and RCE + BP treatments prevented such abnormality with a significantly better result in RCE + BP group which virtually normalized such parameter as well as urinary excretion of DPD. Group C and D reduced the over 20% loss of bone mineral density and bone mineral content/body weight ratio observed in untreated post-ovariectomy group. Untreated ovariectomy caused about 48% decrease of cancellous bone mass in the femoral neck while this abnormality was prevented at similar extent by both RCE and RCE + BP treatments. Ovariectomy determined an over 80% increase of bone alkaline phosphatase (BALP) level but both RCE and RCE + BP treatments significantly mitigated such variable. The BALP decrease yielded by the combined RCE + BP treatment was statistically lower than RCE alone. Taken together these data show that red clover preparation in dosages amenable to clinical practice do improve OVX-induced osteoporosis while a mild metabolic alkalosis might further synergize some therapeutic aspects.

Clinical pharmacology of exogenously administered alkaline phosphatase

PURPOSE

To evaluate the clinical pharmacology of exogenous alkaline phosphatase (AP).

METHODS

Randomized, double-blind, placebo-controlled sequential protocols of (1) ascending doses and infusion duration (volunteers) and (2) fixed dose and duration (patients) were conducted at clinical pharmacology and intensive care units. A total of 103 subjects (67 male volunteers and 36 patients with severe sepsis) were administered exogenous, 10-min IV infusions (three ascending doses) or 24-72 h continuous (132.5-200 U kg(-1) 24 h(-1)) IV infusion with/without preceding loading dose and experimental endotoxemia for evaluations of pharmacokinetics, pharmacodynamics, safety parameters, antigenicity, inflammatory markers, and outcomes.

RESULTS

Linearity and dose-proportionality were shown during 10-min infusions. The relatively short elimination half-life necessitated a loading dose to achieve stable enzyme levels. Pharmacokinetic parameters in volunteers and patients were similar. Innate immunity response was not significantly influenced by AP, while renal function significantly improved in sepsis patients.

CONCLUSIONS

The pharmacokinetics of exogenous AP is linear, dose-proportional, exhibit a short half-life, and are not influenced by renal impairment or dialysis.

Antitumor activity and some immunological properties of gammadelta T-cells from patients with gastrointestinal carcinomas

OBJECTIVES

Human gammadelta T-cells expressing Vgamma2Jgamma1.2Vdelta2-TCR recognize microbial pyrophosphomonoesters in an MHC-independent manner and exert cytotoxic activity on a wide variety of tumor cells. In the present study, the immunological properties of gammadelta T-cells derived from patients with gastrointestinal carcinomas were examined and compared with those from healthy adult individuals, aiming to develop a novel cancer immunotherapy using gammadelta T-cells stimulated with one of the nonpeptide antigens, 2-methyl-3-butenyl-1-pyrophosphate (2M3B1PP).

MATERIALS AND METHODS

Peripheral blood mononuclear cells (PBMs) and tumor-associated lymphocytes (TAL) were obtained from patients with gastrointestinal carcinomas. The mononuclear cells were stimulated with 2M3B1PP for 2 weeks and the expanded gammadelta T cells were examined for cytokine production upon T-cell receptor (TCR) engagement and cytotoxic activity against allogeneic tumors and autologous tumor cells. For comparison, PBMCs derived from healthy adult volunteers were similarly stimulated with 2M3B1PP and the resulting gammadelta T-cells were analyzed for effector functions.

RESULTS

All the peripheral blood- and tumor-associated gammadelta T-cell preparations from patients with gastrointestinal carcinomas proliferated vigorously in response to 2M3B1PP to comparable levels to those from healthy donors. When challenged with CD3 monoclonal antibodies, the carcinoma patient-derived gammadelta T-cells secreted a large amount of inflammatory cytokine, IFN-gamma, and exhibited a potent cytotoxic activity against allogeneic tumor cell lines as well as autologous tumor cells.

CONCLUSION

Both peripheral blood- and tumor-associated gammadelta T-cells derived from patients with gastrointestinal carcinomas were as immunologically active as those from healthy individuals and could be utilized for a novel cancer immunotherapy for gastrointestinal malignancies.

Regulation of STREX exon large conductance, calcium-activated potassium channels by the beta4 accessory subunit

Large conductance (BK-type) calcium-activated potassium channels utilize alternative splicing and association with accessory beta subunits to tailor BK channel properties to diverse cell types. Two important modulators of BK channel gating are the neuronal-specific beta4 accessory subunit (beta4) and alternative splicing at the stress axis hormone-regulated exon (STREX). Individually, these modulators affect the gating properties of the BK channel as well as its response to phosphorylation. In this study, the combined functional consequences of STREX and the mouse beta4 subunit on mouse BK channel biophysical properties were investigated in transfected HEK 293 cells. Surprisingly, we found that the combined effects of STREX and beta4 are non-additive and even opposite for some properties. At high calcium, beta4 and the STREX individually share properties that promote BK channel opening via slowing of deactivation. However, the combined effects are a speeding of deactivation and a decreased open probability. beta4 also inhibits BK channel opening by a slowing of activation. This effect occurs across calcium concentrations in the absence of STREX, but predominates only at low calcium for STREX containing channels. BK channel responses to phosphorylation status are also altered by the combination of the beta4 subunit and STREX. beta4/STREX channels show a slowing of activation kinetics following dephosphorylation whereas beta4 channels lacking STREX do not. In contrast, beta4 confers a speeding of activation in response to cyclic AMP-dependent phosphorylation in channels lacking STREX, but not in channels containing STREX. These results indicate that the combination of the beta4 subunit and STREX confers non-additive and unique properties to BK channels. Analysis of expression in brain slices suggests that STREX and beta4 mRNA overlap expression in the dentate gyrus of the hippocampus and the cerebellar Purkinje cells, suggesting that these unique properties of BK channels may underlie BK channel gating in these cells.

Bone cell responses to the composite ofRicinus communispolyurethane and alkaline phosphatase

The aim of this study was to evaluate the response of osteoblastic cells to the composite of Ricinus communis polyurethane (RCP) and alkaline phosphatase (ALP) incubated in synthetic body fluid (SBF). RCP pure (RCPp) and RCP blended with ALP 6 mg/mL polymer (RCP+ALP) were incubated in SBF for 17 days. Four groups of RCP were tested: RCPp, RCP+ALP, and RCPp and RCP+ALP incubated in SBF (RCPp/SBF and RCP+ALP/SBF). Stem cells from rat bone marrow were cultured in conditions that allowed osteoblastic differentiation on RCP discs and were evaluated: cell adhesion, culture growth, cell viability, total protein content, ALP activity, and bone-like nodule formation. Data were compared by ANOVA or Kruskal-Wallis test. The group RCP+ALP was highly cytotoxic and, therefore, was not considered here. Cell adhesion (p = 0.14), culture growth (p = 0.39), viability (p = 0.46) and total protein content (p = 0.12) were not affected by either RCP composition or incubation in SBF. ALP activity was affected (p = 0.0001) as follows: RCPp < RCPp/SBF < RCP+ALP/SBF. Bone-like nodule formation was not observed on all evaluated groups. The composite RCP+ALP prior to SBF incubation is cytotoxic and must not be considered as biomaterial, but the incorporation of ALP to the RCP followed by SBF incubation could be a useful alternative to improve the biological properties of the RCP.

Oxidative stress reduces renal dopamine D1 receptor-Gq/11alpha G protein-phospholipase C signaling involving G protein-coupled receptor kinase 2

The dopamine D1 receptors (D1R), expressed in renal proximal tubules, participate in the regulation of sodium transport. A defect in the coupling of the D1R to its G protein/effector complex in renal tubules has been reported in various conditions associated with oxidative stress. Because G protein-coupled receptor kinases (GRKs) are known to play an important role in D1R desensitization, we tested the hypothesis that increased oxidative stress in obese Zucker rats may cause GRK2 upregulation and, subsequently, D1R dysfunction. Lean and obese rats were given normal diet or diet supplemented with antioxidant lipoic acid for 2 wk. Compared with lean rats, obese rats exhibited oxidative stress, D1R were uncoupled from G(q/11)alpha at basal level, and SKF-38393 failed to elicit D1R-G protein coupling, stimulate phospholipase C (PLC), and inhibit Na-K-ATPase activity. These animals showed increased basal protein kinase C (PKC) activity and membranous translocation of GRK2 and increased GKR2-G(q/11)alpha interaction and D1R serine phosphorylation. Enzymatic dephosphorylation of D1R restored SKF-38393-induced adenylyl cyclase stimulation but not PLC activation. Treatment of obese rats with lipoic acid restored D1R-G protein coupling and SKF-38393-induced PLC stimulation and Na-K-ATPase inhibition. Lipoic acid treatment also normalized PKC activity, GRK2 sequestration, and GKR2-G(q/11)alpha interaction. In conclusion, these data show that oxidative stress increases PKC activity causing GRK2 membranous translocation. GRK2 interacts with G(q/11)alpha and acts, at least in part, as a regulator of G protein signaling leading to the D1R-G(q/11)alpha uncoupling, causing inability of SKF-38393 to stimulate PLC and inhibit Na/K-ATPase. Lipoic acid, while reducing oxidative stress, normalized PKC activity and restored D1R-G(q/11)alpha-PLC signaling and the ability of SKF-38393 to inhibit Na-K-ATPase activity.

Regulation of the Na+/Ca2+ exchanger (NCX) in the murine embryonic heart

OBJECTIVE

The Na+/Ca2+ exchanger (NCX) is involved in embryonic heart development and function demonstrated by the abnormal myofibrillar organization, defects in heartbeat, and early embryonic death of NCX-null embryos. It was therefore the aim of our study to identify key functional regulators of the embryonic NCX.

METHODS

NCX current (I(NCX)) density was measured as the Ni2+ (5 mM)-sensitive current applying the whole-cell patch-clamp technique in early (EDS, E10.5V) and late developmental stage (LDS, E16.5V) mouse ventricular cardiomyocytes.

RESULTS

Compared to LDS, cardiomyocytes derived from EDS showed a significantly higher basal I(NCX) density for the I(NCX) forward (-120 mV: -4.1+/-1 pA/pF, n=15 versus -1.7+/-0.4, n=11, p<0.05) and reverse modes (+60 mV: 4.0+/-0.9 pA/pF, n=15 versus 1.8+/-0.4, n=11, p<0.05). There was 2-3-fold elevation of forward and reverse current in LDS on application of ATP-gamma-S (2 mM) together with forskolin (1 microM) as well as intracellular application of the catalytic subunit of cAMP-dependent protein kinase (cPKA, 200 U/mL), cAMP (200 microM), phorbol 12-myristate-13-acetate (PMA), a direct activator of protein kinase C (PKC), and 8-Br-cGMP, a membrane permeable analog of cGMP. The specific PKC inhibitor Ro 31-8220 significantly reduced I(NCX) by 70%. Co-application of 20 microM PKA inhibitor Fragment 14-22 (PKI), a specific inhibitor of PKA, and cAMP significantly reduced the exchanger activity by approx 60%. Despite these obvious effects in LDS we could not detect a significant impact of these compounds on I(NCX) in EDS-derived cardiomyocytes. Application of the alkaline phosphatase to test for constitutive phosphorylation of NCX did not affect I(NCX) density in LDS but led to an approx 80% reduction of I(NCX) in EDS.

CONCLUSION

In EDS cardiomyocytes I(NCX) density is upregulated, at least in part by the high phosphorylation of the exchanger protein. At LDS, embryonic cardiomyocytes showed a strong increase of I(NCX) density upon stimulation by PKC- and PKA-dependent signalling pathways.

Investigation of enzymatic behavior of benzonase/alkaline phosphatase in the digestion of oligonucleotides and DNA by ESI-LC/MS

We have developed an ion-pairing HPLC-MS method that has sufficient separation power, selectivity, and sensitivity to investigate the enzymatic behavior of benzonase/alkaline phosphatase upon digestion of oligonucleotides and DNA. Mass spectrometry revealed that this enzyme pair can nonspecifically digest oligonucleotides and DNA into fragments ranging from 2 to 10 nucleotides, i.e., sizes suitable for routine mass spectrometric measurements. Trimers, tetramers, and pentamers are the most prominent digested products. This makes benzonase/alkaline phosphatase a promising choice for DNA and DNA adduct related studies that require a nonspecific enzyme. A computer software program developed in-house was critical in automating the processing of mass spectral data. The methodology described here provides a systematic approach for evaluating the behavior of DNA-cleaving enzymes by mass spectrometry.

Developmental regulation of cardiac MAP4 protein expression

It has been shown that the level of expression of microtubule-associated protein 4 (MAP4) mRNAs changes throughout neonatal heart development [Chapin SJ, et al. 1995. Biochemistry 34:2289]. In the present study, both immunofluorescence and western blotting methods were used to monitor MAP4 protein expression levels in the developing heart. By both methods, it was shown that the levels of total MAP4 protein were maximal during the first postnatal week, and then declined progressively to adulthood. In addition, four major electrophoretic species that reacted with MAP4-specific antibodies (called bands 1-4) were observed in all heart tissue samples. Three of the four bands decreased in abundance throughout postnatal development, but at different rates. The fourth band remained relatively constant in abundance with increasing postnatal age. To determine if phosphorylation events might contribute to this heterogeneity, western blotting experiments using phospho-specific antibodies and phosphatase digestion of extract samples were performed. No phosphorylation-specific antibody staining was observed and no significant changes were demonstrated in the bands after phosphatase treatment, implying that the observed complexity was due mainly to alternative start site or differential isoform expression. Finally, it was discovered that cardiomyocyte MAP4 associated with drug- and cold-stable microtubules in early neonatal myocytes. Thus, the complex regulation of MAP4 protein expression may play a key role in the functional differentiation of myocyte microtubules during heart development.

Beneficial effects of alkaline phosphatase in septic shock

OBJECTIVE

Alkaline phosphatase may decrease the harmful effects of lipopolysaccharide by detoxifying lipid A. The aim of this study was to investigate whether administration of alkaline phosphatase is beneficial in a clinically relevant septic shock model.

DESIGN

Interventional laboratory study.

SETTING

University hospital animal research laboratory.

SUBJECTS

Fourteen fasted, anesthetized, invasively monitored, mechanically ventilated, female sheep (27.6 +/- 3.9 kg).

INTERVENTIONS

Each animal received 1.5 g/kg body weight of feces intraperitoneally to induce sepsis. Ringer's lactate and a 6% hydroxyethyl starch solution were infused throughout the experiment to prevent hypovolemia. Two hours after feces injection, animals were randomized to alkaline phosphatase (60 units/kg intravenous bolus followed by a continuous infusion of 20 units/kg/hr for a total of 15 hrs) or no alkaline phosphatase (control group).

MEASUREMENTS AND MAIN RESULTS

All animals were studied until their spontaneous death or for a maximum of 30 hrs. Plasma alkaline phosphatase concentrations decreased in the control group but increased in the treatment group following alkaline phosphatase administration. In the treatment group, the Pao2/Fio2 ratio was higher (p < .05), blood interleukin-6 concentrations were lower (p < .05), and the survival time was longer (median time 23.8 vs. 17 .0 hrs, p < 0.05) than in the control group. There were no significant differences in systemic hemodynamics or diuresis.

CONCLUSIONS

In this clinically relevant septic shock model, alkaline phosphatase administration improved gas exchange, decreased interleukin-6 concentrations, and prolonged survival time.

Phosphorylation of NMDA NR1 subunits in the myenteric plexus during TNBS induced colitis

N-Methyl-d-aspartic acid (NMDA) receptors are known to function in the mediation of pain and have a significant role in the development of hyperalgesia following inflammation. Serine phosphorylation regulation of NMDA receptor function occurs in a variety of conditions. No studies have demonstrated a change in phosphorylation of enteric NMDA receptors following colonic inflammation. We examined the levels of NMDA NR1 phosphorylation in trinitrobenzene sulfonic acid (TNBS) induced colitis in rats and compared it to protein translation and the development of visceral hypersensitivity. We have previously, demonstrated an increase in the C1 cassette of NR1 mRNA expression at 14, 21, and 28 days following TNBS administration. In this study, we examined the NR1 serine phosphorylation at 14 days following TNBS injection. Male Sprague-Dawley rats (200-250 g) were treated with TNBS (20mg per rat) diluted in 50% ethanol (n=3) and vehicle controls of 50% ethanol (n=3). TNBS and vehicle controls were administered with a 24 gauge catheter inserted into the lumen of the rat colon. The animals were sacrificed at 14 days after induction of the colitis and their distal colon was retrieved for two-dimensional (2D) western blot analysis. Serine phosphorylation of the NR1 subunit with C1 cassette appears at 14 days after TNBS injection. In contrast, there was no NR1-C1 expression in the vehicle controls and untreated normal controls. These results suggest a role for colonic-NMDA receptor phosphorylation in the development of neuronal plasticity following colonic inflammation. Phosphorylation of NR1 may partially explain visceral hypersensitivity present during colonic inflammation.

D1 dopamine receptor hyperphosphorylation in renal proximal tubules in hypertension

A defect in the coupling of the D(1) receptor (D(1)R) to its G protein/effector complex in renal proximal tubules plays a role in the pathogenesis of spontaneous hypertension. As there is no mutation of the D(1)R gene in the spontaneously hypertensive rat (SHR), we tested the hypothesis that the coupling defect is associated with constitutive desensitization/phosphorylation of the D(1)R. The following experiments were performed: (1) Cell culture and membrane preparations from rat kidneys and immortalized rat renal proximal tubule cells (RPTCs); (2) immunoprecipitation and immunoblotting; (3) cyclic adenosine 3',5' monophosphate and adenylyl cyclase assays; (4) immunofluorescence and confocal microscopy; (5) biotinylation of cell surface proteins; and (6) in vitro enzyme dephosphorylation. Basal serine-phosphorylated D(1)Rs in renal proximal tubules, brush border membranes, and membranes from immortalized RPTCs were greater in SHRs (21.0+/-1.5 density units, DU) than in normotensive rats (7.4+/-2.9 DU). The increased basal serine phosphorylation of D(1)Rs in SHRs was accompanied by decreased expression of D(1)R at the cell surface, and decreased ability of a D(1)-like receptor agonist (fenoldopam) to stimulate cyclic adenosine 3',5' monophosphate (cAMP) production. Increasing protein phosphatase 2A activity with protamine enhanced the ability of fenoldopam to stimulate cAMP accumulation (17+/-4%) and alter D(1)R cell surface expression in intact cells from SHRs. Alkaline phosphatase treatment of RPTC membranes decreased D(1)R phosphorylation and enhanced fenoldopam stimulation of adenylyl cyclase activity (26+/-6%) in SHRs. Uncoupling of the D(1)R from its G protein/effector complex in renal proximal tubules in SHRs is caused, in part, by increased D(1)R serine phosphorylation.

Saccharomyces boulardii produces in rat small intestine a novel protein phosphatase that inhibits Escherichia coli endotoxin by dephosphorylation

Using a polyclonal antibody raised against a highly conserved sequence of 38 amino acids containing the activation site (VTDSAAGAT) common to mammalian and yeast alkaline phosphatases (AP), we identified in decapsidated Saccharomyces boulardii a protein phosphatase detected by autoradiography as a single signal (63 kD). Using an affinity chromatography column, the protein phosphatase could be concentrated 39.1-fold and presented as a doublet of two subunits. Compared with rat and bovine purified intestinal AP, the enzyme from S. boulardii had a greater ability to dephosphorylate the lipopolysaccharide (LPS) of Escherichia coli 055B5. When tested in vivo, intraperitoneal injection of intact LPS to rats produced, after 9 h, 100 ng/mL of circulating tumor necrosis factor-alpha with inflammatory lesions and apoptotic bodies in the liver and the heart, whereas rats injected with partially dephosphorylated LPS produced only 40 ng/mL tumor necrosis factor-alpha without organic lesions. In conclusion, S. boulardii is able to inhibit toxicity of E. coli surface endotoxins by the release of a protein phosphatase exhibiting a great capacity of dephosphorylation.

Maximum Phosphorylation of the Cardiac Ryanodine Receptor at Serine-2809 by Protein Kinase A Produces Unique Modifications to Channel Gating and Conductance Not Observed at Lower Levels of Phosphorylation

It is suggested that protein kinase A (PKA)-dependent phosphorylation of cardiac ryanodine receptors (RyR2) is linked to the development of heart failure and the generation of fatal cardiac arrhythmias. It is also suggested that RyR2 is phosphorylated to 75% of maximum levels in heart failure resulting in leaky, unregulated channels gating in subconductance states. We now demonstrate that this is unlikely, as RyR2 isolated from nonfailing cardiac muscle is phosphorylated to 75% of maximum at serine-2809, and in this situation, RyR2 displays low open probability (P(o)) (0.059+/-0.010 [SEM]; n=30) and normal regulation of gating by Ca(2+) and other ligands. However, when serine-2809 is PKA phosphorylated to maximum levels on RyR2, unique changes in channel behavior are observed. The channel displays enhanced single-channel conductance, very long open states causing large increases in P(o), and no evidence of subconductance states. Dephosphorylation of channels by protein phosphatase 1 (from 75% to near 0% at serine-2809) also enhances RyR2 channel activity through abbreviation of closed lifetimes. We propose that channels phosphorylated to 75% of maximum at serine-2809 occupy a natural low point in the RyR2 activity landscape. This optimizes channel control, which can be accomplished either by enhanced or decreased phosphorylation, making the channel particularly sensitive to the kinase:phosphatase balance. Pathological situations such as heart failure might upset this balance and thereby permit prolonged stoichiometric phosphorylation of serine-2809, which would be required for dysregulation of SR Ca(2+) release.

Determination of the phosphorylation level and deamidation susceptibility of equine β-casein

beta-Casein was isolated from Haflinger mare's milk by RP-HPLC, and displayed microheterogeneity by urea-electrophoresis and 2-DE probably due to a variable degree of phosphorylation. To investigate the degree of phosphorylation, the primary structure of equine beta-casein was determined by tryptic hydrolysis and MS of peptides released and by MS of the protein treated by alkaline phosphatase. The molecular mass found for the apo-form of Haflinger mare's beta-casein (25 514 +/- 3 Da) was close to the theoretical mass of the reported sequence (GenBank AAG43954) modified by insertion of a region (residues 27-34) encoded by an exon sometimes out-spliced (25 511.40 Da). Hence, the beta-casein isolated from Haflinger mare's milk corresponded to a variant of 226 amino acid residues. The latter was composed by highly multi-phosphorylated isoforms with three to seven phosphate groups, and pIs, determined by 2-DE, ranging from 4.74 to 5.30. Moreover, the equine beta-casein was able to deamidate spontaneously, at the level of Asn in the potential deamidation motif (135)Asn-Gly(136). Approximately 80% of the protein was deamidated after 96 h of incubation under physiological conditions.

Rat organic anion transporting protein 1A1 (Oatp1a1): purification and phosphopeptide assignment

Rat organic anion transporting protein 1a1 (oatp1a1), a hepatocyte basolateral plasma membrane protein, mediates transport of various amphipathic compounds. Our previous studies indicated that serine phosphorylation of a single tryptic peptide inhibits its transport activity without changing its cell surface content. The site of phosphorylation is unknown and was the subject of the present study. Following immunoaffinity chromatographic purification from rat liver, oatp1a1 was subjected to trypsin digestion and MALDI-TOF. Except for predicted N-glycosylated peptides, 97% of oatp1a1 tryptic peptides were observed. A single tryptic phosphopeptide was found in the C-terminus (aa 626-647), existing in unphosphorylated or singly or doubly phosphorylated forms and sensitive to alkaline phosphatase treatment. The beta-elimination reaction resulted in a mass loss of 98 or 196 Da from this peptide, and subsequent Michael addition with cysteamine increased masses by the predicated 77 and 154 Da, indicating that oatp1a1 can be singly or doubly phosphorylated at serine or threonine residues in the C-terminal sequence SSATDHT (aa 634-640). Subsequent tandem MS/MS analysis revealed that phosphorylation at S634 accounted for all singly phosphorylated peptide, while phosphorylation at S634 and S635 accounted for all doubly phosphorylated peptide. These findings identify the site of oatp1a1 phosphorylation and demonstrate that it is an ordered process, in which phosphorylation at S634 precedes that at S635. The mechanism by which phosphorylation results in loss of transport activity in hepatocytes remains to be established. Whether phosphorylation near the C-terminus inhibits C-terminal oligomerization of oatp1a1, required for normal transport function, can be speculated upon but is as yet unknown.

CREB transcription factor modulates Bcl2 transcription in response to C5a in HL-60-derived neutrophils

BACKGROUND

Complement fragment C5a and neutrophils have been implicated in the pathogenesis of renal disease and C5a has also been shown to delay apoptosis of human neutrophils via a transcription-independent pathway. However, transcription-dependent pathways have not been well described. The present study examined whether activation of HL-60-derived neutrophils by C5a modulates the transcription of two members of the Bcl2 family, Bax (pro-apoptotic) and Bcl2 (anti-apoptotic) molecules, and whether the cAMP-response element-binding protein (CREB) transcription factor mediates these effects through the phosphatidylinositol 3-kinase (PI3K)/Akt and extra-cellular signal-regulated kinase (ERK) signalling pathways.

MATERIALS AND METHODS

The human promyelocytic leukaemia HL-60 cell line was differentiated into neutrophils using 1.25% DMSO. Differentiated cells were incubated with recombinant human C5a for 30-120 min with, or without, pretreatment with wortmannin or PD98059. The cells were lysed and quantified for gene-specific Bax and Bcl2 mRNA. In separate experiments, cells were incubated with C5a for 5-30 min with, or without, pretreatment with wortmannin, PD98059, or alkaline phosphatase. Cells were then lysed and immunoblotted using antihuman phospho-CREB (Ser133) antibody. Apoptosis was assessed by measuring active caspase-3 in differentiated HL-60 cells.

RESULTS

C5a inhibited caspase-3 activation in HL-60-derived neutrophils (P=0.003). C5a significantly increased the expression of Bcl2 mRNA (P=0.028), which was time-dependent, peaking at 30 min, and was abrogated in the presence of either wortmannin or PD98059 (both P=0.028). The C5a had no impact on Bax mRNA expression. The Bax : Bcl2 mRNA ratio markedly decreased at 30 min (P=0.028). Time-dependent effect of C5a on CREB phosphorylation was demonstrable and rapid, peaking at 5 min, and was abrogated by either wortmannin or PD98059 (both P=0.028). Phosphorylation of CREB, but not of Akt and ERK, was inhibited by alkaline phosphatase (P=0.028). The effect of C5a on Bcl2 mRNA expression was abrogated by alkaline phosphatase (P=0.028). The Bax : Bcl2 mRNA ratio markedly increased in the presence of alkaline phosphatase (P=0.046).

CONCLUSIONS

This study demonstrates that C5a induces Bcl2 mRNA transcription in HL-60-derived neutrophils, which is mediated in part by CREB through the convergence of the PI3K/Akt and ERK-signalling pathways.

Characterisation of cryopreserved cells freshly isolated from human bone marrow

Osteoblast progenitor cells (OBPCs) isolated from bone marrow have the ability to differentiate into osteoblasts and thus potential therapeutic use to tissue-engineer bone. In order for OBPCs to be available for clinical use a means of storing viable cells is necessary. The aim of this study was to determine whether a simple method of cryopreservation had an effect on osteogenic differentiation or growth of OBPCs isolated from fresh human bone marrow. Stro-1 was used to identify the isolated OBPCs. The osteoblastic potential of the marrow cells was confirmed as culture with osteogenic supplements (OS) significantly increased osteoblastic protein production (alkaline phosphatase (ALP), osteopontin and osteocalcin) compared with standard conditions (P less than 0.05). Ten further marrow aspirates were harvested; each was halved for either cryopreservation or control culture. Primary cultures from both populations formed colonies with recognised OBPC morphology. OS stimulated both cryopreserved and control populations to produce significantly more osteoblastic proteins (P less than 0.05) and there was no significant difference between the increase in osteogenic proteins when cultured with OS (P great than 0.2). The proliferation rate after 5 days in culture was not significantly affected by cryopreservation (P greater than 0.05). It has been suggested that OBPCs are immuno-privileged; so allogenic cells could be implanted into patients for tissue engineering bone without causing a hypersensitivity reaction. Our study demonstrates a method of storage, which allows OBPCs to be available for use without affecting osteoblastic potential or viability.

Phosphorylation of the homeotic tumor suppressor Cdx2 mediates its ubiquitin-dependent proteasome degradation

The Caudal-related homeodomain transcription factor Cdx2 plays a key role in intestinal cell fate determination. Reduction of Cdx2 expression is a feature of many human colon carcinomas and inactivation of one cdx2 allele facilitates the development of invasive adenocarcinoma in the murine colon. Here, we investigated the post-translational regulation of Cdx2. We showed that various forms of Cdx2 coexist in the intestine and colon cancer cell lines, some of them being phosphorylated forms. We found that cyclin-dependent kinase 2 phosphorylated Cdx2 in vitro and in vivo. Using site-specific mutagenesis, we identified serine 281 as a new key residue for Cdx2 phosphorylation. Intriguingly, serine 281 belongs to a conserved motif of four evenly spaced serines (the 4S motif) similar to the one controlling beta-catenin degradation by the proteasome pathway. A nonphosphorylated mutant Cdx2 lacking the 4S motif (4S>A) exhibited reduced polyubiquitination upon proteasome inhibition and increased stability compared to wild-type Cdx2. In addition, we found that this mutant was less efficient to suppress colony formation than wild-type Cdx2. Thus, our data highlight a novel post-translational mechanism controlling Cdx2 degradation via phosphorylation and polyubiquitination, which may be of importance for intestinal development and cancer.