Bacillus Calmette–Guérin in Immuno-Regulation of Alzheimer’s Disease

Bacillus Calmette–Guérin is frequently the treatment of choice of superficial bladder cancer. Exposing the urinary bladder of elderly patients with bladder cancer to the BCG vaccine reduced the risk of Alzheimer’s disease (AD) substantially. Vaccines against other infectious microorganisms by other vaccination methods showed a similar but a lesser effect. This suggests that immune effects on AD are antigenically non-specific, likely being a metabolic result of immune system activation, similar to that shown for Juvenile diabetes. In this mini review we point to the benefit of BCG vaccine. We then briefly highlight the pathological involvement of the immune system in the AD both, in the peripheral and the central (brain) compartments. Given the uncertain prophylactic mechanism of the BCG effect against AD we propose to take advantage of the therapeutically planned bladder exposure to BCG. Based on pathological aggregation of wrongly cleaved amyloid precursor protein (APP) resistant to the unfolded protein response (UPR) which results in amyloid beta plaques we predict that BCG may impact the UPR signaling cascade. In addition pathways of innate immunity training concerned with energy metabolism, predict capability of activated immune cells to substitute deranged astrocytes that fail to support neuronal energy metabolism. This mini review points to ways through which immune cells can mediate between BCG vaccination and AD to support the wellness of the central nervous system.

Vulnerable and Resilient Phenotypes in a Mouse Model of Anorexia Nervosa

BACKGROUND

Increased physical activity is a common feature of anorexia nervosa (AN). Although high activity levels are associated with greater risk of developing AN, particularly when combined with dieting, most individuals who diet and exercise maintain a healthy body weight. It is unclear why some individuals develop AN while most do not. A rodent model of resilience and vulnerability to AN would be valuable to research. Dopamine, which is believed to play a crucial role in AN, regulates both reward and activity and may modulate vulnerability.

METHODS

Adolescent and young adult female C57BL/6N mice were tested in the activity-based anorexia (ABA) model, with an extended period of food restriction in adult mice. ABA was also tested in dopamine transporter knockdown mice and wild-type littermates. Mice that adapted to conditions and maintained a stable body weight were characterized as resilient.

RESULTS

In adults, vulnerable and resilient phenotypes emerged in both the ABA and food-restricted mice without wheels. Vulnerable mice exhibited a pronounced increase in running throughout the light cycle, which dramatically peaked prior to requiring removal from the experiment. Resilient mice exhibited an adaptive decrease in total running, appropriate food anticipatory activity, and increased consumption, thereby achieving stable body weight. Hyperdopaminergia accelerated progression of the vulnerable phenotype.

CONCLUSIONS

Our demonstration of distinct resilient and vulnerable phenotypes in mouse ABA significantly advances the utility of the model for identifying genes and neural substrates mediating AN risk and resilience. Modulation of dopamine may play a central role in the underlying circuit.

Newborn BCG vaccination complemented by boosting correlates better with reduced juvenile diabetes in females, than vaccination alone

Type 1 diabetes (T1D), like other autoimmune diseases, is on the rise since the second half of the 20th century. Hypothetically this has been ascribed to restricted exposure to microbial diversity due to advanced hygienic practices accompanying modernization, and increasing prosperity in urban versus rural habitats. The autoimmune animal model of T1D, inhibited by Bacillus Calmette Guerine (BCG), motivated testing the impact of BCG on T1D incidence in humans. Several epidemiological analyses, short of one, failed to demonstrate a protective effect of BCG against T1D. The present retrospective analysis of two data sets reevaluates the hypothetic inhibitory effect of BCG on human T1D. Reassessment of data from a Swedish study reveals that a single BCG vaccination provided a small but significant protection against T1D. A second data set of T1D prevalence/1000 Israeli military conscripts, from a doctoral thesis presenting 17 birth cohorts at age 17 is evaluated against the national schedule of vaccination related to years of birth. To correct for the annual increasing T1D trend the mean urbanization (census) rate was set as an annual moving average and factored into the prevalence (T1D/1000) of respective birth cohorts. Three groups of cohorts corresponding to BCG vaccination are presently identified; Group A corresponds to the years in which newborns were vaccinated and boosted if necessary, at age 12. Group B corresponds to the period when boosting was discontinued. Group C corresponds to years when newborn BCG vaccination was discontinued. T1D (only in females) was slightly but significantly lower in group B (n = 5 cohorts) versus C (n = 8 cohorts, p = 0.0475, by Mann Whitney U test). T1D in group A (n = 4 cohorts) was lower than in group B (p = 0.02). This analysis supports the hypothesis that in human females postnatal BCG vaccination, reinforced by boosting, has a protective impact on T1D being superior to omitted boosting, which in its turn is still better than stopping vaccination altogether. This analysis further suggests that upon advanced modernization the BCG vaccine compensates for reduced exposure to microbial diversity early in life.

Bacillus Calmette-Guérin (BCG) therapy lowers the incidence of Alzheimer's disease in bladder cancer patients

BACKGROUND

Alzheimer's disease (AD) affects one in ten people older than 65 years. Thus far, there is no cure or even disease-modifying treatment for this disease. The immune system is a major player in the pathogenesis of AD. Bacillus Calmette-Guérin (BCG), developed as a vaccine against tuberculosis, modulates the immune system and reduces recurrence of non-muscle invasive bladder cancer. Theoretical considerations suggested that treatment with BCG may decrease the risk of AD. We tested this hypothesis on a natural population of bladder cancer patients.

METHODS AND FINDINGS

After removing all bladder cancer patients presenting with AD or developing AD within one-year following diagnosis of bladder cancer, we collected data on a total of 1371 patients (1134 males and 237 females) who were followed for at least one year after the diagnosis of bladder cancer. The mean age at diagnosis of bladder cancer was 68.1 years (SD 13.0). Adjuvant post-operative intra-vesical treatment with BCG was given to 878 (64%) of these patients. The median period post-operative follow-up was 8 years. During follow-up, 65 patients developed AD at a mean age of 84 years (SD 5.9), including 21 patients (2.4%) who had been treated with BCG and 44 patients (8.9%) who had not received BCG. Patients who had been treated with BCG manifested more than 4-fold less risk for AD than those not treated with BCG. The Cox proportional hazards regression model and the Kaplan-Meier analysis of AD free survival both indicated high significance: patients not treated with BCG had a significantly higher risk of developing AD compared to BCG treated patients (HR 4.778, 95%CI: 2.837-8.046, p = 4.08x10-9 and Log Rank Chi-square 42.438, df = 1, p = 7.30x10-11, respectively). Exposure to BCG did not modify the prevalence of Parkinson's disease, 1.9% in BCG treated patients and 1.6% in untreated (Fisher's Exact Test, p = 1).

CONCLUSIONS

Bladder cancer patients treated with BCG were significantly less likely to develop AD at any age than patients who were not so treated. This finding of a retrospective study suggests that BCG treatment might also reduce the incidence of AD in the general population. Confirmation of such effects of BCG in other retrospective studies would support prospective studies of BCG in AD.

Assessing Cellular Stress and Inflammation in Discrete Oxytocin-secreting Brain Nuclei in the Neonatal Rat Before and After First Colostrum Feeding

The goal of this protocol is to isolate oxytocin-receptor rich brain nuclei in the neonatal brain before and after first colostrum feeding. The expression of proteins known to respond to metabolic stress was measured in brain-nuclei isolates using Western blotting. This was done to assess whether metabolic stress-induced nutrient insufficiency in the body triggered neuronal stress. We have previously demonstrated that nutrient insufficiency in neonates elicits metabolic stress in the gut. Furthermore, colostrum oxytocin modulates cellular stress response, inflammation, and autophagy markers in newborn rat gut villi prior to and after first feed. Signaling protein markers associated with the endoplasmic reticulum stress [ER chaperone binding immunoglobulin protein (BiP), eukaryotic translation initiation factor 2A (eIF2a), and eIF2a kinase protein kinase R (p-PKR)], as well as two inflammation-signaling proteins [nuclear factor-κB (NF-kB) and inhibitor κB (IkB)], were measured in newborn brain nuclei [nucleus of the solitary tract (NTS), paraventricular nucleus (PVN), supra-optic nucleus (SON), cortex (CX), striatum nuclei (STR), and medial preoptic nucleus (MPO)] before the first feed (unprimed by colostrum) and after the start of nursing (primed by colostrum). Expression of BiP/GRP78 and p-eIF2a were upregulated in unprimed and downregulated in primed NTS tissue. NF-kB was retained (high) in the CX, STR, and MPO cytoplasm, whereas NF-kB was lower and unchanged in NTS, PVN, and SON in both conditions. The collective BiP and p-eIF2 findings are consistent with a stress response. eIf2a was phosphorylated by dsRNA dependent kinase (p-PKR) in the SON, CX, STR, and MPO. However, in the NTS (and to a lesser extent in PVN), eIf2a was phosphorylated by another kinase, general control nonderepressible-2 kinase (GCN2). The stress-modulating mechanisms previously observed in newborn gut enterocytes appear to be mirrored in some OTR-rich brain regions. The NTS and PVN may utilize a different phosphorylation mechanism (under nutrient deficiency) from other regions and be refractory to the impact of nutrient insufficiency. Collectively, this data suggests that brain responses to nutrient insufficiency stress are offset by signaling from colostrum-primed enterocytes.

Colostrum oxytocin modulates cellular stress response, inflammation, and autophagy markers in newborn rat gut villi

Little is known about the role of oxytocin (OT) in colostrum during early gut colonization. We previously showed that transient OT receptor (OTR) expression on newborn rat enterocytes coincides with the milk-suckling period, and that OT activates endoplasmic reticulum stress sensors in cultured enterocytes. Here, we explored whether colostrum-OT attenuates stress in newborn villi primed and unprimed by colostrum by measuring levels of stress markers including BiP (an ER chaperone), eIF2a (translation initiation factor), and pPKR (eIF2a kinase). We also measured two inflammation-signaling proteins NF-κB and its inhibitor IκB. To test the impact of colostrum on autophagy, we measured a marker of autophagy initiation, LC3A. Colostrum increased inactive p-eIF2a, p-PKR and IκB and reduced p-IκB, BiP and LC3A. LPS increased and OT decreased p-IkB. BiP (GRP78) was higher in unprimed than primed villi. Together, these data suggest that colostrum OT attenuates the impact of inflammation on postnatal gut villi and that OT enhances autophagy to protect against amino acid insufficiency-induced stress during the interval between birth and the first feeding.

Oxytocin opposes effects of bacterial endotoxin on ER-stress signaling in Caco2BB gut cells

BACKGROUND

The neuropeptide neuromodulator and hormone oxytocin (OT) activates signaling pathways involved in mRNA translation in response to endoplasmic reticulum stress and reduces inflammation associated with experimental colitis in rats. The anti-inflammatory effects of OT may serve a vital role in the development, survival and function of newborn-type enterocytes during microbial gut colonization, which coincides with the milk suckling period when OT receptor expression peaks in the gut. Furthermore, mice deficient in the OT receptor have abnormal gut structure and function, underscoring OT's developmental importance.

METHODS

We tested the effect of OT upon lipopolysaccharide (LPS)-induced markers of the inflammatory response in Caco2BB gut cells in vitro using automated immunocapillary electrophoresis.

RESULTS

We demonstrate that OT suppresses NF-κB signaling and presumably inflammatory transcriptional programs, which are unleashed by LPS through the modulation of IκB. We show that OT counteracts LPS-elicited silencing of the unfolded protein response, a pathway limiting endoplasmic reticulum stress by suppressing protein translation. OT selectively activates dsRNA-activated kinase (PKR), X-box binding protein 1 (XBP1), immunoglobulin binding protein (BiP), A20 (TNFα-induced protein 3) and inositol requiring enzyme 1a (IRE1a). OT inactivates eukaryotic translation initiation factor 2a (eIF2a) without significant activation of protein kinase RNA-like endoplasmic reticulum kinase (PERK).

CONCLUSIONS

Mild, preemptive stimulation of endoplasmic reticulum stress sensors by OT may precondition newborn enterocytes to resist apoptosis associated with inflammation and may support their differentiation and development by modulating cellular metabolism.

GENERAL SIGNIFICANCE

OT may protect enterocytes and other cell types, such as neurons, from stress-related complications during postnatal development.

Oxytocin modulates markers of the unfolded protein response in Caco2BB gut cells

We have shown that oxytocin receptor (OTR) expression in neonatal rat enterocytes is robust from birth to weaning, but OTR function during this period is unknown. We previously reported that oxytocin (OT) stimulation of Caco2BB cells (enterocytes in vitro) inhibits the mammalian target of rapamycin complex 1 (mTORC1) signaling. The unfolded protein response (UPR) is known to protectively reduce translation during endoplasmic reticulum (ER) stress. Because the mTORC1 pathway is linked to cellular stress, we investigated markers of UPR in OT-stimulated Caco2BB cells. We report that OT modulates several factors involved in sensing and translation of ER stress. High OT (62.5 nM) reduced translation initiation factor 4E-BP1 phosphorylation (Ser65), which is known to inhibit cap-dependent translation via its rate-limiting eukaryotic translation initiation factor 4E (eIF4E). Importantly, high OT increased phosphorylation of eukaryotic translation initiation factor 2a (eIF2a) phospho-Ser51, which inhibits eIF2a. High OT also increased protein kinase RNA-like endoplasmic reticulum kinase phosphorylation, a sensor of ER stress and a kinase of eIF2a. Both high and low OT activated inositol requiring enzyme1 (IRE1), which generates the transcription factor X-box binding protein 1 (XBP1) and induces the UPR. We also show that OT modulates XBP1 splicing and induces tribbles 3 (TRIB3; a negative regulator of Akt and protein involved in autophagy) and immunoglobulin binding protein (BiP; ER-chaperone). Taken together, these results indicate that OT modulates sensors of ER stress and autophagy. These findings support our hypothesis that transiently elevated OTR expression in neonatal gut may serve a protective function during a critical postnatal developmental period.

Oxytocin modulates mTORC1 pathway in the gut

Our recent findings of a weaning-related pattern of oxytocin (OT) and OT receptor (OTR) expression in the rat enteric nervous system and in villus-crypt enterocytes, together with the known high level and stability of OT in breast milk support that OT may play a role in gut function and development. We previously described a biphasic dose-response of the PI3K/Akt pathway in gut cells treated with OT. Activation peaked at 62.5 nM OT (30 min) and coincided with OTR internalization. Here we use automated Western blotting to further explore OT-elicited changes in Akt and pAkt(T308), as well as in downstream substrates p70 S6 kinase-1 (S6K1) and eIF-4E binding protein 1 (4E-BP1). Relative to fresh growth medium (FGM) alone, our results showed OT in FGM reduced the abundance and phosphorylation of S6K1 and the phosphorylation of 4E-BP1, both substrates of mammalian target of rapamycin complex 1 (mTORC1). Phosphorylation of mTORC1 regulator, Raptor(S792), was increased by high and low OT concentrations, with predicted inhibitory effects on mTORC1. OT thus downregulates anabolic effects induced by FGM activity catalyzed by mTORC1. OT is a regulator of the PI3K/Akt/mTORC1 pathway in Caco2BB cells and may modulate translation in gut cells.

All-trans-retinoic acid mediates changes in PI3K and retinoic acid signaling proteins of leiomyomas

OBJECTIVE

To detect changes induced by all-trans-retinoic acid (ATRA) on the expression and activation of target proteins of the retinoic acid (RA) and PI3K/Akt pathways involved in leiomyoma growth.

DESIGN

A study on human tissue cultures.

SETTING

Hadassah University Hospital.

PATIENT(S)

Premenopausal women with uterine leiomyomas.

INTERVENTION(S)

Paired cultures of normal myometrium and leiomyomas, from women undergoing hysterectomy, were obtained.

MAIN OUTCOME MEASURE(S)

The effect of ATRA was examined on the expression and phosphorylation of relevant RA, PI3K/Akt, and Bcl2 proteins (immunochemical analysis), cell proliferation, cell cycle distribution, and apoptosis.

RESULT(S)

Applying our cell culture model, we demonstrated that ATRA induced changes in the expression and activation of the RA and PI3K/Akt pathway proteins in leiomyoma cells, with significant increases of alcohol dehydrogenase 1 and cyclin D2 protein levels. In part of the leiomyoma cells, ATRA induced a relative increase of Bax (proapoptotic) as well as a relative decrease of phosphorylated glycogen synthase kinase 3β (proapoptotic).

CONCLUSION(S)

Our results highlight the involvement of ATRA in the RA and PI3K/Akt pathways, whose specific signaling products may influence the outcome of leiomyoma growth by regulating cell proliferation, apoptosis, and survival. These results might be useful for the on-going research into alternative methods for treating and preventing this disorder.

Structural changes and cellular localization of resuscitation-promoting factor in environmental isolates of Micrococcus luteus

Dormancy among nonsporulating actinobacteria is now a widely accepted phenomenon. In Micrococcus luteus, the resuscitation of dormant cells is caused by a small secreted protein (resuscitation-promoting factor, or Rpf) that is found in "spent culture medium." Rpf is encoded by a single essential gene in M. luteus. Homologs of Rpf are widespread among the high G + C Gram-positive bacteria, including mycobacteria and streptomycetes, and most organisms make several functionally redundant proteins. M. luteus Rpf comprises a lysozyme-like domain that is necessary and sufficient for activity connected through a short linker region to a LysM motif, which is present in a number of cell-wall-associated enzymes. Muralytic activity is responsible for resuscitation. In this report, we characterized a number of environmental isolates of M. luteus, including several recovered from amber. There was substantial variation in the predicted rpf gene product. While the lysozyme-like and LysM domains showed little variation, the linker region was elongated from ten amino acid residues in the laboratory strains to as many as 120 residues in one isolate. The genes encoding these Rpf proteins have been characterized, and a possible role for the Rpf linker in environmental adaptation is proposed. The environmental isolates show enhanced resistance to lysozyme as compared with the laboratory strains and this correlates with increased peptidoglycan acetylation. In strains that make a protein with an elongated linker, Rpf was bound to the cell wall, rather than being released to the growth medium, as occurs in reference strains. This rpf gene was introduced into a lysozyme-sensitive reference strain. Both rpf genes were expressed in transformants which showed a slight but statistically significant increase in lysozyme resistance.

Ultrasound-diagnosed puerperal osteopenia in young primiparas

OBJECTIVE

To study whether osteopenia occurs following pregnancy and to evaluate its severity in young primiparas.

STUDY DESIGN

A prospective case control study. Sixty-one young primigravidae early after birth and 59 nulligravidae matched for age and BMI participated in the study. Bone status was examined using ultrasonic bone transmission velocity over the tibia; Z-score and T-score for bone density were calculated. Serum bone alkaline phosphatase, osteocalcin and urinary N-telopeptide crosslinks were evaluated as bone remodeling biochemical markers.

RESULTS

Ultrasonic parameters of bone status following delivery were significantly lower in the puerperal group as compared to the nulligravida group. Serum mean bone alkaline phosphatase levels and urinary N-telopeptide crosslinks secretion were higher by 50% in the puerperal group, while serum osteocalcin levels were significantly lower (by 25%) than in the nulligravida controls. A positive correlation between ultrasonic measurements and biochemical markers was demonstrated in the postpartum group, whereas the control group showed a negative correlation.

CONCLUSION

Women at their early puerperium demonstrate a significant cortical bone mass reduction as measured by ultrasonograph and markers of bone turnover. It appears that pregnancy is a state of unbalanced accelerated bone turnover that may be associated with reduced osteoblastic activity.

Cytotoxicity of NF-κB inhibitors Bay 11-7085 and caffeic acid phenethyl ester to Ramos and other human B-lymphoma cell lines

OBJECTIVE

The viability of normal and malignant B-cells was shown to depend on the constitutive activation of the nuclear factor (NF)- kappaB pathway. Thus, attempts to find efficient inhibitors of NF-kappaB play a central role in the search for novel anti-B lymphoma therapies. We studied the effects of two NF-kappaB inhibitors, Bay 11-7085 (BAY) and caffeic acid phenethyl ester (CAPE), on the viability of B-lymphoma cell lines.

METHODS

We investigated the mechanism(s) of the cytotoxic effect of the NF-kappaB inhibitors, BAY, and CAPE on human-lymphoma and nonhematological cell lines.

RESULTS

BAY and CAPE were shown to kill Ramos-Burkitt's lymphoma cells with IC(50) values of 0.7 microM and 4 microM, respectively. The rapid killing by BAY (h) vs the slower killing by CAPE (1-3 days), and their differential effects on the stages of the cell cycle, indicated that these drugs induce killing by different mechanisms. BAY and CAPE induced a loss of the cytoplasmic compartment and generated pyknotic nuclei, which lacked nuclear or nucleosomal fragmentation, features characteristic of necrosis rather than apoptosis. BAY also induced a rapid loss of the mitochondrial potential and rapid inhibition of p65 NF-kappaB binding to its kappaB motif without reducing the level of nuclear p65.

CONCLUSION

Our results indicate that BAY causes a necrotic rather than apoptotic cell death, either through its effect on the NF-kappaB pathway and/or by affecting additional molecular targets. The high sensitivity of B-lymphoma cell lines to the cytotoxicity of BAY, justify further research to explore its potential therapeutic effect on human B lymphomas.

Multiple origins of cultivated grapevine (Vitis vinifera L. ssp. sativa) based on chloroplast DNA polymorphisms

The domestication of the Eurasian grape (Vitis vinifera ssp. sativa) from its wild ancestor (Vitis vinifera ssp. sylvestris) has long been claimed to have occurred in Transcaucasia where its greatest genetic diversity is found and where very early archaeological evidence, including grape pips and artefacts of a 'wine culture', have been excavated. Whether from Transcaucasia or the nearby Taurus or Zagros Mountains, it is hypothesized that this wine culture spread southwards and eventually westwards around the Mediterranean basin, together with the transplantation of cultivated grape cuttings. However, the existence of morphological differentiation between cultivars from eastern and western ends of the modern distribution of the Eurasian grape suggests the existence of different genetic contribution from local sylvestris populations or multilocal selection and domestication of sylvestris genotypes. To tackle this issue, we analysed chlorotype variation and distribution in 1201 samples of sylvestris and sativa genotypes from the whole area of the species' distribution and studied their genetic relationships. The results suggest the existence of at least two important origins for the cultivated germplasm, one in the Near East and another in the western Mediterranean region, the latter of which gave rise to many of the current Western European cultivars. Indeed, over 70% of the Iberian Peninsula cultivars display chlorotypes that are only compatible with their having derived from western sylvestris populations.

Preparation of low density lipoprotein from large apheresis cartridges for induction of cell death in Saos2 osteoblasts

Atherosclerosis is epidemiologically associated with postmenopausal osteoporosis presumably by common etiologic factors, reflecting a state of comorbidity in aging. Osteoblasts make a significant facet of this comorbidity state. The present study shows that LDL (native and oxidized) separated by conventional density ultracentrifugation induces osteoblast cell growth arrest in culture. Since the density unltracentrifugation is a tedious procedure we examined, in the present study, the option of LDL purification by ionic strength elution from LDL-apheresis cartridges. We tested the ability of LDL and oxidized LDL (oxLDL) from apheresis columns to induce apoptosis in human Saos2 osteoblasts. Isotonic NaCl effluent washed from LDL-apheresis columns (before starting elution of LDL) induced cell proliferation. In some of the effluent fractions that stimulated Saos2 osteoblasts, up to 15% of the stimulation levels could be significantly inhibited with antilipoprotein A antibodies. After the isotonic washing (150 mM NaCl), upon elution with high ionic strength, 0.2-0.3 M NaCl, some front-runner LDL eluate fractions also induced cell growth and others did not inhibit Saos2 cell growth. This indicates that these fractions might have been contaminated with apolipoprotein A or with other mitogenic compounds. In contrast, the late-to-elute (last 1/3) LDL portion, with a mean density of 1.042 g/mL, killed the cells as expected. This suggests that only the very last one third of LDL eluted by high ionic strength (0.3-0.5 M) is free of osteoblast-mitogenic compounds or lipoprotein-A containing particles. This approach to LDL purification might serve as a convenient and economic method for studying the composition of individual LDL particles and their interaction with cells in culture.

LDL induces Saos2 osteoblasts death via Akt pathways responsive to a neutral sphingomyelinase inhibitor

Atherosclerosis is epidemiologically associated with postmenopausal osteoporosis (OP) presumably by common etiologic factors, reflecting a state of co-morbidity in aging. Osteoblasts make a significant facet of this co-morbidity state. Since oxidized low-density lipoprotein (oxLDL) is a major factor in generation of vascular wall pathology, we examined the ability of native LDL (nLDL) and oxLDL to induce Saos2 osteoblasts growth arrest. OxLDL induced Saos2 cell death with morphological features of apoptosis that was inhibited mainly by caspase-9 and partially by caspase-3 but not by caspase-8 inhibitors. nLDL, like oxLDL, has induced cell death, where 60% (P = 0.00033) and 30% (P = 0.075, ns) of the cell death, respectively, could be inhibited by scyphostatin (a neutral sphingomyelinase [nSMase] inhibitor). Upon similar condition, nLDL inhibited the phosphorylation of Akt and two of its downstream targets, fork head receptor (FKHR) and glycogen synthase kinase-3 (GSK3). This is a pathway that stimulates cell survival and proliferation. nLDL has also induced an increase in the proapoptotic Bcl-Xs and it has diminished the potential antiapoptotic Src kinase activity. At the 4 h time-point, upon a substantial decrease in nLDL-induced Akt phosphorylation, scyphostatin has inhibited the reduction in FKHR and GSK3 phosphorylation but inexplicably not that of Akt. Scyphostatin has also corrected the reduction in Src kinase activity. Taken together, the results indicate that nLDL has induced apoptosis in Saos2 osteoblasts by inactivation of the pathway downstream to Akt using nSMase, and by involvement of Src kinase. Inferring that caspase-9 was the main executioner (rather than caspase-8 and-3) in Saos2 cell death, indicates that the nSMase-induced release of ceramide, directly activated the intrinsic mitochondrial apoptotic pathway. With regard to the Akt inactivation by nLDL, Saos2 osteoblasts responded in an opposite fashion to the response reported by others, in macrophages.

Micrococcus luteus -- survival in amber

A growing body of evidence now supports the isolation of microorganisms from ancient materials. However, questions about the stringency of extraction methods and the genetic relatedness of isolated organisms to their closest living relatives continue to challenge the authenticity of these ancient life forms. Previous studies have successfully isolated a number of spore-forming bacteria from organic and inorganic deposits of considerable age whose survival is explained by their ability to enter suspended animation for extended periods of time. However, despite a number of putative reports, the isolation of non-spore-forming bacteria and an explanation for their survival have remained enigmatic. Here we describe the isolation of non-spore-forming cocci from a 120-million-year-old block of amber, which by genetic, morphological, and biochemical analyses are identified as belonging to the bacterial species Micrococcus luteus. Although comparison of 16S rRNA sequences from the ancient isolates with their modern counterparts is unable to confirm the precise age of these bacteria, we demonstrate, using complementary molecular and cell biological techniques, evidence supporting the view that these (and related modern members of the genus) have numerous adaptations for survival in extreme, nutrient-poor environments, traits that will assist in this bacteria's persistence and dispersal in the environment. The bacteria's ability to utilize succinic acid and process terpine-related compounds, both major components of natural amber, support its survival in this oligotrophic environment.

The AG1478 tyrosine kinase inhibitor is an effective suppressor of leiomyoma cell growth

BACKGROUND

Uterine leiomyomas are the most common benign smooth muscle cell tumours in women. Formation of leiomyomas, still not completely understood, is viewed as a multistep process, with involvement of ovarian steroid hormones, cytokines and growth factors. Our study aimed to identify tyrosine kinase inhibitors as potential 'signal transduction therapeutics' for leiomyomas, underlying the effect of ovarian steroidal hormones.

METHODS

The selective epidermal growth factor (EGF) receptor blocker AG1478 was evaluated as a potential target, since EGF has been shown to mediate estrogen action and to play a crucial role in regulating leiomyoma growth. Paired cultures of leiomyoma and normal myometrium samples were established and the suppressive effect of AG1478 on the cells prior and subsequent to steroidal hormone treatment was examined: cell proliferation, recovery after treatment, cell cycle analysis and immunochemical analysis of relevant proteins.

RESULTS

Leiomyoma cell growth is effectively blocked by AG1478 and is unaffected by the presence of physiological concentrations of progesterone and estradiol. AG1478 (10 microM) completely suppressed proliferation and the cells did not recover after cessation of treatment.

CONCLUSION

The growth-arresting properties of AG1478, unaffected by ovarian steroidal hormones, identify it as a potential lead agent for the non-surgical management of uterine leiomyomas.

Cell death in cultured human Saos2 osteoblasts exposed to low-density lipoprotein

Osteoporosis (OP) and atherosclerotic-cardiovascular diseases (and possibly dementia) constitute emerging age-related co-morbidity states that might share risk factors. Blood-born lipids, like LDL involved in atherosclerosis and apolipoprotein-E4 (ApoE4) involved in dementia, may also be implicated in development of OP. We examined osteoblast cell lines as a culture model for OP by exposure to lipoproteins. ApoE expression in Saos2 and U2OS osteoblasts was confirmed by PCR. ApoE4 did decrease cell counts relatively to ApoE3, especially in Saos2 cells in which it was less selective for cells with higher alkaline phosphatase (ALP, an osteoblast marker) activity than ApoE3. This associates with ApoE4, being a risk factor for both dementia and OP. Saos2, but not U2OS, showed a decrease in cell counts after 48 h exposure to native LDL (NLDL). Both cell lines had decreased cell counts already after 24 h when exposed to oxidized-LDL (OxLDL) for which Saos2 also showed a higher sensitivity than U2OS. Exposure of Saos2 to both, OxLDL at low concentration (5 microg/ml) and NLDL revealed a shrunken size cell fraction of 17-23% on the fluorescence-activated cell sorter (FACS) analysis. Such shrunken cell fraction was not seen when Saos2 cells were exposed to 50 microg/ml of OxLDL or to OxLDL combined with 10 nM dexamethasone (DEX, a stimulator of osteoprogenitor differentiation). DEX treatment has lysed the cells earlier than 24 h post exposure and has selected more resistant cells that did not show apoptotic shrinkage in the FACS analysis done after 24 h. We interpret this as a failure to detect the apoptotic cell fraction due to their lysis prior to the FACS analysis. Western blots performed at different time points (10 min, 30 min, 4 h, 24 h, and 48 h) under OxLDL + DEX revealed a fall in the positive regulator of pp60Src-kinase phosphotyrosine (pY)418 relative to the DEX controls during the first 4 h. This is consistent with DEX osteogenic induction, known to be negatively regulated by c-Src, although the pY418/pY529 ratios (negative/positive kinase regulation) fell only at the 10 min time point. Contrarily the pY418/pY529 ratio increased, relative to untreated controls, under 5 microg/ml and 50 microg/ml of NLDL at the 4 h time point and under 50 microg/ml NLDL only at the 10 min time point, being consistent with the ability of a higher dose of LDL to antagonize osteoblast differentiation. This could be even more acceptable if the NLDL would have become minimally oxidized during its long purification procedure. Under NLDL, the Bcl-2/Bax ratio was pro-apoptotic at 10 min, 30 min, and 4 h only under 50 microg/ml, whereas under OxLDL + DEX it was pro-apoptotic only after 4 h suggesting that additional pathways contribute to cell death. These results indicate that lipid effects on human osteoblast lines in culture may be used as a model to identify molecular targets shared between OP and atherosclerosis for intervention in this co-morbidity.

Inhibitors that target protein kinases for the treatment of ovarian carcinoma

OBJECTIVE

Ovarian cancer is the leading cause of death from gynecologic malignancies in the United States. In an attempt to develop drugs that suppress ovarian cancer cells, we examined the effect of selective inhibitors of protein tyrosine kinases-tyrphostins, which are likely to play a role in ovarian cancer cells.

STUDY DESIGN

We examined the cellular and biochemical effects of tyrphostins AG1478, PP2, AGL2592, and AG490 from four different families on the ovarian carcinoma cell line OV1063.

RESULTS

We found that the AG1478, PP2, AGL2592, and AG490 tyrphostins suppressed cell proliferation and altered cell cycle distribution of the OV1063 cells in a dose- and time-dependent manner. Immunoblotting analysis indicated that AG1478 effectively inhibited epidermal growth factor receptor autophosphorylation, that AG490 decreased the level of Jak2 and phosphorylated Stat3, and that PP2 decreased the level of pp60Src protein. AGL2592 decreased the level of constitutive activated epidermal growth factor receptor and pStat3, but its molecular targets have not been identified completely.

CONCLUSION

The growth-arresting properties of these tyrphostins identify them as possible candidates for signal transduction therapy.

Tyrosine kinase inhibitors suppress the growth of non-hodgkin B lymphomas

Non-Hodgkin lymphomas usually become resistant to chemotherapy and relapse due to the their intense antiapoptotic robustness. Furthermore, the slow growth of these malignancies limits the effectiveness of drugs aimed mainly at the proliferative pathways. Because protein tyrosine kinases (PTKs) play a key role in both proliferative and antiapoptotic pathways we screened our library of PTK inhibitors for agents that induce growth arrest and apoptosis in non-Hodgkin B cell lymphoma cell lines. Herein, we describe the identification of a family of PTK inhibitors whose most potent member is AGL 2592. This agent induces growth arrest and massive apoptosis in a number of non-Hodgkin lymphoma cell lines. We also show that the lymphoma cell lines are much more sensitive to this class of agents compared with other malignant carcinoma cells. AGL 2592 induces a dose-dependent and time-dependent inhibition of tyrosine phosphorylation of numerous proteins, including Stat3, and an increase of Bcl-2 phosphorylation, both biochemical hallmarks of growth inhibition and apoptosis.

Inhibitors of tyrosine kinases in the treatment of psoriasis

Psoriasis is a heterogenous skin disease, characterized by epidermal hyperproliferation, abnormal keratinization and inflammation. The heterogeneity of the disease results probably from the interaction of multiple gene abnormalities with environmental factors. The new approaches to drug design have become refocused to the emerging understanding of the role of signaling pathways in health and disease. Protein tyrosine kinases (PTKs) regulate cell proliferation, differentiation and immune processes. Uncontrolled signaling from receptor and intracellular tyrosine kinases can lead to numerous proliferative diseases: cancer, leukemia, restenosis and psoriasis. Identification of PTKs that play a key role in a defined disease can lead to a selective drug. The balance of signals which regulate the homeostasis of normal epidermis is altered in psoriasis. Several lines of evidence suggest a role for the EGF receptor system in this process. Therefore, blockers of the EGFR kinase were suggested as potent antipsoriasis agents. PTK inhibitors from the tyrphostin family were found to block EGF - dependent cell proliferation. AG 1571 (SU 5271) potently inhibits ligand-induced autophosphorylation of EGF-R, downstream signal transduction events, DNA replication and cell cycle progression at micromolar concentrations, as well as proliferation of keratinocytes isolated from psoriatic lesions in excellent correlation with its EGFR kinase inhibitory activity in these cells. AG 1571 (SU 5271) has been in clinical trials by SUGEN Inc. since early 1997. Overexpression of the EGFR is the hallmark of most epithelial cancers. Therefore one can view blockers of the EGFR kinase as becoming universal inhibitors. Tyrphostins are the first signal transduction agents to be used in the clinic. This article summarizes recent progress in the development of PTK inhibitors in the treatment of psoriasis.

Isolation and hormonal responsiveness of primary cultures of human bone-derived cells: gender and age differences

We present a model for isolating human cell culture derived from biopsies obtained during orthopedic surgery. Four donor groups were defined by gender and age: pre- and postmenopausal women (<50 and >55 years, respectively), and younger (30-55 years) and older (>60 years) men. Bone-derived cells were identified as osteoblasts by major osteoblastic characteristics; that is, high alkaline phosphatase (ALP) activity, dose-dependent increase of ALP by 1,25(OH)2D3, high levels of parathyroid hormone (PTH)-induced cyclic AMP, and 1,25-(OH)2D3-induced osteocalcin. In all cells, levels of osteocalcin were significantly elevated (p < 0.05 and 0.01). In cells derived from men, no significant age differences were found in ALP and osteocalcin values of basal activity and in fold stimulation 1,25(OH)2D3. Cells from postmenopausal women showed a nonsignificant lower basal ALP activity than premenopausal cells. In postmenopausal cells, ALP responded less to 1,25(OH)2D3 (33% increase, p < 0.05) than the premenopausal cells (100% increase, p < 0.05). In cells from either age group, ALP did not respond to the gonadal steroids 17beta-estradiol (E2) and dihydrotestosterone (DHT) or progesterone. Basal levels of osteocalcin were higher in cells of premenopausal origin as compared with postmenopausal cells (p = 0.05), but response to 1,25(OH)2D3 was the same. PTH significantly stimulated cAMP (p = 0.001) in all age and gender groups analyzed. In all groups, no differences were found in either basal activity or in PTH response. Unlike men, cells derived from the bone of women were more susceptible to age changes. We postulate that the postmenopausal cell population had a decreased number of osteoblasts, or cells in a lower differentiation stage. These results extend our knowledge of bone biology found in animal models and reveal that human osteoblasts from men do not show the same age-dependent differences observed in women.

Growth inhibition of psoriatic keratinocytes by quinazoline tyrosine kinase inhibitors

Psoriasis is characterized by hyperproliferation of keratinocytes associated with an inflammatory infiltrate in the epidermis. Among factors which may be related to hyperplasia of psoriatic keratinocytes is the persistent autocrine stimulation of the epidermal growth factor receptor (EGFR) by transforming growth factor-alpha. Owing to the pivotal role of the EGFR in driving the growth of human psoriatic keratinocytes, we examined two selective inhibitors of EGFR kinase activity: 4-(3-bromophenylamino)-6, 7-dimethoxyquinazoline (AG1517/SU5271) and 4-(3-chlorophenylamino)-6, 7-dimethoxyquinazoline (AG1478) on psoriatic keratinocytes. SU5271 potently inhibits ligand-induced autophosphorylation of EGFR, and downstream signal transduction events, including DNA replication and cell cycle progression. SU5271, at micromolar concentrations, inhibited the proliferation of keratinocytes isolated from psoriatic lesions in excellent correlation with its EGFR kinase inhibitory activity in these cells. Biologically active concentrations of SU5271 penetrated human cadaver skin, suggesting that this compound is a strong candidate as an antipsoriatic agent.

Serum-mediated osteogenic effects of head injury on cultured rat marrow stromal cells

Central nervous system (CNS) injuries in humans are frequently associated with heterotopic ossification (HO) and with enhanced fracture healing. In search for an experimental HO model we tested sera, from an established rat model of closed head injury (CHI), for their osteogenic effects on rat marrow stromal cells. Most normal rat sera increased cell proliferation not discriminating between osteoprogenitors and other stromal cells. Rats followed longitudinally by sequential blood sampling were bled 24 hours before and 24 hours, 48 hours, and 7 days after CHI. Sera obtained 24 and 48 hours after CHI progressively decreased cell proliferation and specific alkaline phosphatase (ALP) activity compared with pre-CHI sera of the same rats. Sera obtained from these rats, 7 days post-CHI, partially recovered proliferation induction, more than recovering induction of specific ALP activity. A positive correlation between day 11 ALP activity and day 21 mineralization was found under stimulation by pre-CHI sera. However, no correlation was found on stimulation with sera obtained 48 hours after CHI. Correlation between ALP and mineralization partially recovered in cultures exposed to sera obtained 7 days after CHI. In cross-sectional experiments where rats were subjected to single blood sampling, sera of 24 hours and 7 days post-CHI induced proliferation, whereas sera of 48 hours and 14 days post-CHI did not. The results indicate that 48 hours post-CHI, the mitogenicity of sera decreased in both cross-sectional and longitudinal blood sampling. In addition, 48 hours post-CHI, the specific ALP activity increases in cultured marrow stromal cells. Thus, changes in bone-seeking factors, causing serum-mediated osteogenic activity in rats, are expected close on 48 hour post-CNS injury.

Tyrphostins that suppress the growth of human papilloma virus 16-immortalized human keratinocytes

Human papilloma virus 16 (HPV16) is considered to be the causative agent for cervical cancer, which ranks second to breast cancer in women's malignancies. In an attempt to develop drugs that inhibit the malignant transformation of HPV16-immortalized epithelial cells, we examined the effect of tyrphostins on such cells. We examined the effect of tyrphostins from four different families on the growth of HPV16-immortalized human keratinocytes (HF-1) cells. We found that they alter their cell cycle distribution, their morphology, and induce cell death by apoptosis. The effects of tyrphostins on HF-1 cells are different from their effects on normal keratinocytes. Growth suppression by AG555 and AG1478 is accompanied by 30% apoptosis in HF-1 cells, but this is not observed in normal keratinocytes. Tyrphostin treatment produces distinctive morphological changes in HF-1 cells and in normal keratinocytes; however, the culture organization of normal keratinocytes is less disrupted. These differential effects of the tyrphostins on HPV16-immortalized keratinocytes compared with their effects on normal keratinocytes suggests that these compounds are suitable candidates for the treatment of papilloma. Previous and present results indicate that group 1 tyrphostins, which inhibit Cdk2 activation, and group 2 tyrphostins, represented by AG1478, a potent epidermal growth factor receptor kinase inhibitor, induce cell cycle arrest; and, in the case of HF-1 cells, apoptosis and differentiation. Cells accumulate in the G(1) phase of the cell cycle at the expense of S and G(2) + M. These compounds block the growth of normal keratinocytes without inducing apoptosis or differentiation, causing them to accumulate in G(1). AG17, which belongs to group 4, exerts its antiproliferative effect mainly by increasing the fractions of cells in G(1) with a concomitant decrease in the fraction of cells in S and G(2) + M.

Induction of bone formation in rat osteoprogenitor cell culture by sera of climacteric women before and after hormone replacement therapy

OBJECTIVE

To evaluate the effect of hormone replacement therapy (HRT) on growth and differentiation of cultured osteoprogenitor cells.

DESIGN

Prospective clinical study.

SETTING

Outpatients in a menopause clinic.

PATIENT(S)

Women with climacteric symptoms.

INTERVENTION(S)

Daily oral conjugated estrogen, 0.625 mg, and medroxyprogesterone acetate, 2.5 mg, for 7-12 months. Bone density measurement before HRT and blood sampling before and after HRT.

MAIN OUTCOME MEASURE(S)

Sera of climacteric women were added to the culture of rat osteoprogenitor cells, and indices of cell proliferation and differentiation (alkaline phosphatase activity and mineralization) were measured before and after HRT.

RESULT(S)

Sera after HRT significantly decreased cell counts but not alkaline phosphatase activity or mineralization as compared with sera before HRT. However, mineralization induced in the bioassay by both sera showed a positive correlation (r = 0.56) with E2 levels before treatment and a negative correlation (r = -0.6181) with time in menopause of serum donors. The change in mineralization showed a significant correlation with hip bone mineral density z scores (r = -0.67) but not with spine z scores (r = -0.1915), whereas the change in cell count correlated with spine bone mineral density z scores (r = 0.49) only.

CONCLUSION(S)

Changes in serum-induced cell proliferation and mineralization may be helpful in studying the response to HRT in climacteric women. Serum-induced mineralization is more efficient in diagnosing osteopenia than in monitoring HRT effects.

Opposing effects of cyclosporin A and tyrphostin AG-1478 indicate a role for Src protein in the cellular control of mineralization

Cyclosporin A (CsA) induces osteoporosis but not through direct activation of osteoclasts. CsA also inhibits cell-mediated mineralization in marrow stromal cell culture, whereas the tyrphostin AG-1478 increases mineralization. These antagonistic effects on mineralization were used to discern molecules that underwent phosphorylation changes in association with their opposing effects on mineralization. In parallel, quantitative changes in Src protein were followed. Multiple dexamethasone (DEX)-stimulated stromal cell cultures were grown with and without a mineralization-inhibiting dose (0.1 microM) of CsA and were harvested on different days of DEX stimulation. Immunoblots of gel-fractionated cell extracts showed that the most noticeable changes in tyrosine phosphorylated proteins (TPP) were seen on day 8 of DEX stimulation. At least 15 TPP bands, mostly smaller than 53 kDa, were more prominent in CsA-treated cultures on day 8. Under CsA, Src protein quantity decreased on day 8, but its cleavage product (52/54 kDa) was sixfold more abundant then on day 7. Day 8 was chosen to test the effect of AG-1478 on the CsA-induced TPP changes. Dimethyl sulfoxide (DMSO) alone, the solvent of AG-1478, increased mineralization in CsA-treated versus CsA-untreated cultures and slightly decreased Src and its cleavage product. AG-1478 at 5 microM, in CsA cultures increased the specific alkaline phosphatase activity threefold, with a slight change in mineralization relative to controls grown with DMSO alone. This was accompanied by decreased intensity of several TPP bands smaller than 36 kDa. In contrast, treatment with 50 microM of AG-1478 increased the intensity of TPP bands at the same molecular size range. This high AG-1478 dose decreased cell counts selecting mineralizing cells. The results indicate that increased Src protein cleavage product on day 8 by CsA is associated with mineralization inhibition, which is opposed by DMSO and 50-microM AG-1478, thus antagonizing the effect of CsA on mineralization. Direct or indirect interaction between Src and TPP, antagonistically affected by CsA and AG-1478, is likely to underlay cellular control of mineralization. Changes in p19 and p29 intensity showed association with mineralization that was reflected by a significant direct and inverse correlation, respectively, with calcium precipitation per cell.

Src protein and tyrosine-phosphorylated protein profiles in marrow stroma during osteogenic stimulation

Src protein is essential for the regulation of bone turnover primarily via bone resorption because it is required in osteoclast differentiation and function. We followed temporal changes of Src protein abundance in marrow stromal cells induced to mineralize by dexamethasone (DEX), growth in cold temperature, or both. Given the tyrosine kinase function of Src and its numerous substrates, profiles of phosphotyrosine-containing proteins were followed as well. On day 11 of stimulation, specific alkaline phosphatase (ALP) activity at 30 degrees C decreased under DEX relative to 37 degrees C cultures, in accord with increased cell counts. Mineralization per well under DEX increased by 25% at 37 degrees C, whereas at 30 degrees C it increased by more than threefold regardless of the DEX stimulation. At 30 degrees C, on a per cell basis mineralization increased 2.5 and 3 times with and without DEX, respectively. Cultures at 37 degrees C showed a general drop per cell of many phosphotyrosine-containing proteins on day 3 relative to days 1 and 2 in both DEX-stimulated and nonstimulated cultures; several proteins did recover (recuperate) thereafter. On days 1 and 2, the phosphotyrosine signal was higher in several proteins under DEX stimulation; this trend became inverted after day 3. The changes in abundance per cell of Src protein (pp60src) followed a similar trend, and in addition a truncated Src molecule, p54/52src, was detected as a putative cleavage product presumably representing its carboxy terminus. The pp60src was most abundant, relative to its truncated product, in day 7 nonstimulated cultures, whereas under DEX stimulation the truncated species pp54/52src showed the highest relative abundance on days 7. At 30 degrees C, DEX stimulation accentuated the increase in Src protein on day 3, showed no change on day 7, and returned to increase Src protein on day 10. Potassium ionophorvalinomycin, considered to select against mineralizing osteoprogenitors at 30 degrees C, showed on day 10 in the absence of DEX a relative increase in truncated Src protein compared to both DEX-stimulated and nonstimulated cultures in the absence of valinomycin. On day 7 of DEX stimulation, the presence of valinomycin resulted in low p54/52src. Among phosphotyrosine-containing proteins, a 32-34 kDa band, as yet unidentified, showed the most concordant changes with mineralization induction. P32-34 decreased by DEX on days 2 and 8 and increased by low temperature alone or combined with DEX on day 3. On day 7, p32-34 did not change under DEX, but valinomycin selected cells with less phoshpotyrosine-containing p32-34. Taken together, high Src abundance at the start of osteogenic induction followed by a decrease 1 week later is probably related to energy metabolism-dependent induction of mineralization. This is in temporal accord with the increase in Src truncation and fluctuation in mitochondrial membrane potential (which affects mineralization). The reported binding of amino-terminal Src oligopeptide to p32 ADP/ATP carrier in the mitochondrial inner membrane raises the question of its possible involvement in mitochondria-regulated mineralization.

Structurally different bisphosphonates exert opposing effects on alkaline phosphatase and mineralization in marrow osteoprogenitors

Bisphosphonates (BPs) are inhibitors of bone resorption and soft tissue calcification. The biological effects of the BPs in calcium-related disorders are attributed mainly to their incorporation in bone, enabling direct interaction with osteoclasts and/or osteoblasts through a variety of biochemical pathways. Structural differences account for the considerable differences in the pharmacological activity of BPs. We compared the effects of two structurally different compounds, alendronate and 2-(3'-dimethylaminopyrazinio)ethylidene-1,1-bisphosphonic acid betaine (VS-6), in an osteoprogenitor differentiation system. The BPs were examined in a bone marrow stromal-cell culture system, which normally results in osteoprogenitor differentiation. The drugs were present in the cultures from days 2 to 11 of osteogenic stimulation, a period estimated as being comparable to the end of proliferation and the matrix-maturation stages. We found that the two different BPs have opposing effects on specific alkaline phosphatase (ALP) activity, on stromal-cell proliferation, and on cell-mediated mineralization. These BPs differentially interact with cell-associated phosphohydrolysis, particularly at a concentration of 10(-2) of ALP Km, in which alendronate inhibits whereas VS-6 did not inhibit phosphatase activity. VS-6 treatment resulted in similar and significantly increased mineralization at 10 and 1 microM drug concentrations, respectively. In contrast, mineralization was similar to control, and significantly decreased at 10 and 1 microM drug concentrations, respectively, under alendronate treatment.

Opposing effects of tyrosine kinase inhibitors on mineralization of normal and tumor bone cells

Induction of matrix maturation and mineralization in calcified tissues is important for patients with primary bone tumors and other bone deficiencies, e.g., osteoporosis. For the former it signifies a better prognosis in osteosarcoma, and for the latter it might improve bone remodeling. In the present study we exposed osteosarcoma cells (Saos2), normal bone cells, and marrow stroma to two different tyrosine kinase (TK) inhibitors: AG-555 and AG-1478. These tyrphostins differ in their effect on signal transduction downstream to the TK receptor (RTK): AG-1478 inhibits src family TKs whereas AG-555 inhibits nuclear TKs. We found that both tyrphostins at 50 microM increased specific alkaline phosphatase (ALP) activity in Saos2 cells. AG-555 abrogated mineralization whereas AG-1478 increased it. Similarly, in human bone-derived cell cultures the same dose of tyrphostins had an opposing effect on mineralization but, in contrast to AG-555, AG-1478 positively selected cells with ALP activity. These tyrphostins also differed in their effect on rat marrow stromal cells. AG-555 decreased cell counts unselectively, whereas the decreased cell counts by AG-1478 resulted in selection of osteoprogenitor cells as indicated by a concordant increase in specific ALP activity. The effect of a lower dose of AG-1478, 5 microM, on the increase in mineralization exceeded its own efficiency in selecting cells with specific ALP activity. Our results indicate that AG-1478 selects and preserves the osteoblastic phenotype, at doses moderately higher than those required to induce mineralization, and substantially higher than the doses required for RTK inhibition. Identification of downstream molecular targets for AG-1478, in marrow stromal cells, might prove useful in designing more selective drugs, capable of separating proliferative from differentiation-inducing activities.

Cyclosporin A and its non-immunosuppressive derivative exhibit a differential effect on cell-mediated mineralization in culture

Chronic immunosuppressive treatment with cyclosporin A (CsA) is associated with decreased bone density. However, in culture, CsA inhibits osteoclast differentiation and bone resorption. This raises the question as to whether CsA also affects osteoblast function. Immunophilin, one of the CsA-binding cyclophilins that is implicated in the immunosuppressive action of CsA via calcineurin, is a peptidyl prolyl cis-trans isomerase (PPl). CsA also binds a mitochondrial membrane PPl which is implicated in controlling permeability transition pores. Therefore, in the present study we tested the effect of CsA on cell mediated mineralization in parallel with mitochondrial rhodamine retention as an indicator of mitochondrial membrane potential Rat marrow stromal cells were grown in dexamethasone (DEX) medium to stimulate mineralization in culture, and CsA was added to various cultures using different treatment schedules. Low dose (0.1 microM) CsA inhibited mineralization, compared to controls, when present in the cultures during days 3-11 of DEX stimulation. Contrarily, high dose CsA (1.0 microM) resisted the inhibitory effect of the low dose. SDZ 220-384 (SDZ), a non-immunosuppressive derivative of CsA which is known, like CsA, to bind to mitochondrial cyclophilin but does not inhibit calcineurin, was also tested. Both high and low doses of SDZ decreased mineralization when present in the cultures from day 3 or from day 0. The similar effect of the low CsA dose and SDZ on mineralization is in accord with their ability to block permeability transition pores. The differential effect, on day 21 mineralization, between high CsA dose and SDZ took place in parallel to their opposing effects on mitochondrial membrane potential. On days 4-8, mitochondrial rhodamine retention was higher under CsA than under SDZ. Under these conditions there was no significant difference between the effects of these drugs on cell proliferation measured on day 11; there was a minor decrease in specific alkaline phosphatase activity by SDZ, too small to explain the extent of mineralization inhibition by SDZ. These results suggest that permeability transition pores might be involved in controlling mineralization. Unlike SDZ, CsA exhibits an additional effect on the mitochondrial membrane potential and on mineralization when applied at a high dose on day 3. Therefore identifying the additional activity of high dose CsA, which is missing in SDZ, may be beneficial. Such activity is expected to resist changes in rhodamine retention and decreased mineralization induced by SDZ, and yet enable preservation of immunosuppressive activity of CsA.

Cell-mediated mineralization in culture at low temperature associated with subtle thermogenic response

In both the growth plate and in marrow stromal cell cultures cell-mediated mineralization is preceded by characteristics of anaerobic and low efficiency energy metabolism. Reagents that increase mineralization like malonate and dexamethasone (DEX) also increase the mitochondrial membrane potential (MtMP) especially 1 week after DEX stimulation. Contrarily, levamisole, which decreases mineralization, also decreases MtMP. Modulation of MtMP and energy metabolism could be linked to regulation of mineralization by the uncoupling of oxidative phosphorylation. This uncoupling should be associated with thermogenesis in cells that induce mineralization. We examined whether cold temperature affects mineralization, and whether cellular thermogenesis takes place at cold temperature in parallel to changes in MtMP. Osteoprogenitor cells (OPC) induced, in DEX stimulated rat marrow stroma, higher mineralization at 33 degrees C than at 37 degrees C. Increased mineralization by cold temperature required long incubation since incubation in the cold during short intervals, 3-4 days, did not increase mineralization relative to (37 degrees C) controls. Marrow stromal cells in the presence of valinomycin responded to incubation at 33 degrees C by retaining all the vital dye after 4 h, unlike the cells at 37 degrees C; however, after 24 h the level of dye retention at 33 degrees C was the same as at 37 degrees C. The delayed response of the temperature-dependent (> 37 degrees C) K+ ionophor to incubation in the cold indicated that certain cells may respond to low temperature by local intracellular heating, and by heat conduction to the plasma membrane. DEX-stimulated stromal cells, unlike unstimulated cells, showed increased mitochondrial rhodamine 123 retention in the presence of valinomycin after 24 h in the cold, which corresponds to day 4 of OPC induction. This is consistent with the concept that valinomycin-induced cell damage is mediated by (cold-induced) local heating. The mechanism of this cell damage should selectively prefer nonthermogenic (rhodamine retaining) over thermogenic (rhodamine leaking) cells such as OPC. At cold temperature DEX-stimulated stromal cells showed the best anti-OPC selection under exposure to valinomycine between days 3-7, concurrent with the period of rhodamine leakage from the mitochondria. These results indicate that thermogenesis is enhanced during the period of low MtMP in mineralizing cells, and prolonged exposure to cold increases mineralization also due to induction of subtle thermogenesis.

Differential induction of cell-mediated mineralization in rat marrow stroma by sera from women of low and high risk for vertebral fracture

The purpose of this study was to analyze the ability of sera to reflect the state of bone metabolism by testing the osteogenic response of mesenchymal cells in culture. Sera of 20 peri- and postmenopausal women were tested before the initiation of hormone replacement therapy. The responding cells were osteoprogenitors (OPC) of rat marrow stroma which normally respond to dexamethasone (DEX) and beta-glycerophosphate (beta GP) by proliferation, differentiation, and mineralization in culture. Instead of DEX, diluted sera (1:50) were applied to rat stromal cell cultures for analysis of their ability to affect cell proliferation, specific alkaline phosphatase (ALP) activity, and cell-mediated mineralization. The results were compared individually with the respective values of vertebral bone mineral density (BMD), expressed as the number of standard deviations above or below the mean BMD of reference populations (positive or negative Z-score). Serum donors were divided in two; the group with positive Z-scores was considered to have a low risk, and that with negative Z-scores was considered to have a higher risk for vertebral fractures. No significant difference was found between the two groups in the ability of their sera to induce cell proliferation or specific ALP activity. However, sera representing negative Z-scores induced sixteenfold less mineralization than those of positive Z-scores. The scatter of individual mineralization values was highly discriminatory between the two groups (alpha < 0.00). These results indicate that the serum-induced, cell-mediated mineralization in culture might be suitable for initial evaluation of fracture risk and thus deserve further investigation.

Opposing effects on mitochondrial membrane potential by malonate and levamisole, whose effect on cell-mediated mineralization is antagonistic

The act of chondrocyte preparation for primary, enchondral, mineralization is associated with a decline in mitochondrial respiration toward the end of the proliferative zone and the hypertrophic zone in the growth plate. Dexamethasone (Dex)-stimulated cultures of rat marrow stroma constitute a differentiation model simulating, in its energy metabolism, chondrocyte mineralization. In this model, early inhibition of succinate dehydrogenase (SDH) enriches the culture with mineralizing cells, whereas levamisole inhibits mineralization. Dex also increases mitochondrial membrane potential in stromal cells, especially on days 7-8 of stimulation. In the present study, suicide inhibition of SDH, by nitropropionic acid (NPA), in Dex-stimulated cells showed a dose-dependent increase in day 21 mineralization; the maximal effect was induced on days 2-4 of stimulation. Mineralization under 2-day-long exposure to NPA showed a similar trend to the previously studied effect of continuous exposure to malonate applied between days 3-11. Unlike malonate, the effect of NPA required its presence in the cultures for only 2 days and resulted in higher mineralization than that seen under 8 days of malonate. NPA delineated a period, days 2/4 to 7/9, in which inhibition of succinate oxidation is necessary to augment mineralization. During this period, NPA also exhibited OPC selection capacity. Early application of levamisole, under conditions previously shown to decrease day 21 mineralization, maintained mitochondrial membrane potential at the beginning of Dex stimulation but decreased or had little effect on it during days 5-10. By contrast, malonate previously found to increase day 21 mineralization decreased the membrane potential at the beginning of Dex stimulation but increased it later on day 7, or during days 5-10. These results indicate that during osteoprogenitor differentiation, before the mineralization stage, a surge in mitochondrial inner membrane potential during late matrix maturation may be a marker that heralds the extracellular matrix mineralization.

Analysis of cell-mediated mineralization in culture of bone-derived embryonic cells with neurofibromatosis

von Recklinghausen neurofibromatosis (NF1) is an autosomal dominant genetic disorder associated with congenital pseudoarthrosis and with short stature. To examine whether the NF1 phenotype includes functional osteogenic defects, embryonic bone-derived cells affected with NF1 were tested in culture for specific alkaline phosphatase (ALP) activity and cell-mediated mineralization and compared with other embryonic bone derived cells. NF1 showed a relatively higher specific ALP activity, which has further increased in response to dexamethasone + beta-glycerophosphate (beta GP) (Dex medium) coordinately with a decrease in cell proliferation. In In the control group, two samples showed increased ALP activity, one showed decreased activity and the forth one did not show any change in ALP. NF1 cells were distinguished from other cells regarding day 21 mineralization, they did not mineralize when cultured with ascorbate alone in the absence of Dex medium, whereas control cells did mineralize. Adding beta GP resulted in mineralization by NF1 cells but less than in other cells. In addition, NF1 cells responded to dexamethasone by increasing the beta GP-induced mineralization, as opposed to cells from other embryonic bones, which either did not respond or have even decreased mineralization under dexamethasone. Upon cis-hydroxyproline exposure, Dex medium has also distinguished NF1 cell ALP activity from that of other cell origins. Inhibition of respiratory complex II by malonate showed that most embryonic bone-derived cells of 12 weeks gestation are malonate resistant; thus, malonate selection was ineffective. This is in contrast to rat marrow stromal cells previously shown to undergo mineralizing cell enrichment in response to malonate. Exposure to levamisole, of Dex-treated cells, at days 0-11 has inhibited day 21 mineralization in all tested cultures in spite of the increase in day 11-specific ALP activity. Both malonate and levamisole did not distinguish NF1 cells from the osteogenic phenotype of other cells. Essentially embryonic bone-derived cells from 12 weeks gestation, cultured in the absence of beta GP, retained their mineralization capacity, which does not increase under dexamethasone, as distinguished from NF1 cells which require beta GP for mineralization and positively respond to dexamethasone. Therefore, bone-derived NF1 cells may be useful for studying the regulation of the mineralization process.

Tibial implant mineralization in rats is inversely related to serum osteogenic capacity

In this study, the correlation between the mineralization of healing bone defects and the osteogenic capacity of the serum was tested in rats. The purpose of the study was to test the hypothesis that during callus formation, some serum factors are consumed. The bone defects in the tibia contained two different implant types, and all sustained juxta-implant fractures. One implant type was the coral Porites and the other was its recrystallized version (Interpore-200), which exhibit different mineralization rates during fracture healing. Use of these two implant types permitted generation of an expanded mineralization spectrum suitable for regression analysis. Mineralization was assessed by measuring the mineral content change (MCC) using dual-energy X-ray absorptiometry. Osteogenic capacity of sera of the implanted rats was assessed by its ability to increase specific alkaline phosphatase (ALP) activity in stromal cell cultures. The MCC was followed for 5 weeks in the Porites and Interpore-200 implants, and it was found that the MCC in Interpore-200 implants exceeded that of the Porites implants. Thus, the two implant types generated a wide mineralization spectrum. Induction of ALP in stromal cell culture was lower for sera derived from rats implanted with Interpore-200 than for sera derived from rats implanted with Porites. Two weeks after implantation, the change in serum ALP induction correlated inversely with the MCC of bone defects. This indicates that during callus formation, the mineralization rate is reciprocally related to the serum osteogenic capacity. The decreased serum osteogenic capacity may be interpreted by the hypothesis that callus formation consumes certain serum osteogenic factors.

Marrow stromal cell commitment to mineralization under the effect of a prolyl hydroxylase inhibitor

Mitochondrial response to the effect of a hydroxylase (PH) inhibitor was tested in marrow stromal cells during stimulation of osteoprogenitor cell (OPC) differentiation. The rationale for this was to explore pathways of regulatory interactions between procollagen synthesis and mitochondrial respiration that could be linked to the commitment of OPCs to mineralization. Stimulated OPCs exposed to the PH inhibitor cis-hydroxyproline (cis-HP), compared to the noninhibiting isomer trans-HP, for 11 days showed a dose-dependent decrease in cell proliferation, the surviving cells showed increased alkaline phosphatase activity. Trans-HP did not influence the cis-HP effect on ALP and on proliferation arrest. Short time exposures, 2-3 days, to cis-HP at different periods suggested that Days 0-3 and 3-5 were critical for the commitment to Day 21 mineralization of OPCs. On Days 0-3 cells were most sensitive to cis-HP, since on Day 11, 8 days after removal of cis-HP, they were too scarce to be counted by the staining method. However, the presence of 5.0 mM cis-HP in the cultures during Days 3-5 has induced on Day 21 close to 24-fold more mineralization/cell than controls, compared to the trans-HP effect, which was only close to 3-fold. The presence of cis-HP in the cultures on Days 0-3 has augmented the mitochondrial Day 3 retention of rhodamine 123 (Rho) in the stromal cells, relative to controls, compared to the presence of trans-HP. However, the presence of cis-HP during Days 3-5 or 3-6 resulted in lower Day 5 Rho retention, relative to controls, which was not significantly different from the retention that resulted from trans-HP. Since Rho retention is related to the final result of aerobic respiration level, these results are interpreted as a cis-HP inhibitory effect on procollagen peptidyl-proline hydroxylation, which may in turn release oxygen surpluses, to be available for mitochondrial consumption. The fall in Rho retention responses to cis-HP between Days 0-3 and 3-5 is suggesting either abrupt decrease in proline hydroxylation or poor mitochondrial sensitivity to oxygen in Day 3-5 cultures.

Induction of osteoprogenitor cell differentiation in rat marrow stroma increases mitochondrial retention of rhodamine 123 in stromal cells

Bone marrow stromal cells contain colony forming cells with the potential to differentiate into osteoprogenitor (OPC) cells. OPC-stimulation medium, containing dexamethasone, ascorbate, and beta-glycerophosphate is widely used to recruit OPCs in culture. Cultures were incubated 24 h with rhodamine 123 (Rho), on different days, to examine the effect of the OPC-stimulation medium on the mitochondrial membrane potential of stromal cells. Cultures grown in both ordinary medium (DMEM with 15% FCS) and OPC-stimulation medium showed 2 Rho retention peaks on days 3-4 and 10-11. Between days 5 and 10 there was a drop in Rho retention/cell. OPC-stimulation medium increased Rho retention by at least twice the amount relative to ordinary medium, and has quadrupled it on day 7. Incubation with Rho concentrations above 5.0 micrograms/ml inhibited the portion of increased Rho retention which was contributed by the OPC-stimulation medium. Prolonged exposure to 0.1, 1.0, and 10.0 micrograms/ml Rho for 12 days only slightly increased day 12 ALP activity/cell, had no effect on day-21 mineralization and only the high dose, 10.0 micrograms/ml, doubled stromal cell proliferation. Under 24 h incubation Rho concentrations of 1.0 microgram/ml and below can serve as a marker for mitochondrial membrane potential in differentiating stromal cells. The results indicate that under both culture conditions stromal cell mitochondria undergo cycles of high and low membrane potential states and that the OPC-stimulation medium constantly maintains an elevated membrane potential relative to ordinary medium.

Studies of the levamisole inhibitory effect on rat stromal-cell commitment to mineralization

The ability of Levamisole to decrease mineralization in skeletal tissue is usually related to its effect on alkaline phosphatase (ALP). However, Levamisole is also suspected to diminish mineralization by an additional mechanism which is unrelated to the ALP control of apatite crystal growth. To delineate the time in differentiation during which Levamisole inhibits mineralization, a tissue culture model system of bone marrow stromal cells was used. Secondary cultures of stromal cells were propagated in osteoprogenitor cell (OPC) induction medium for three weeks, followed by measurement of calcium precipitation. In situ ALP assays at pH 7.6 were also performed. When cells were cultured with 0.2 mM Levamisole for three weeks, Day 20 values of calcium precipitates were lower than in controls, but Day 20 ALP values were paradoxically higher. The correlation between calcium and ALP within each group was low. The correlation slightly improved, in uninhibited cultures, when Day 21 calcium values were matched with earlier Day 12 ALP values. This suggested the existence of a Levamisole-sensitive mechanism for mineralization inhibition effective prior to the culture's mineralization stage. To focus on this early effect on mineralization Levamisole was added to stromal cultures on different days and removed on Day 12. Levamisole decreased Day 21 mineralization when added on Days 0, 3, 5, and 7, but not when added on Day 9. The Levamisole-induced inhibition of mineralization was accompanied by an increase in Day 12 ALP specific activity, compared to controls, when added from Day 5 and thereafter. The results indicate that part of the ability of stromal cells to mineralize is determined during the first week of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Selection of malonate-resistant stromal cell-derived osteoprogenitor cells in vitro

Bone marrow stromal cells give rise to osteoprogenitor cell (OPC) colonies, with characteristic mineralized bone nodules in vitro. During differentiation, OPCs in the culture are surrounded by heterogeneous populations of various cell lineages and by different OPC differentiation stages. In the present study, attempts were made to increase the homogeneity of OPCs in culture. The reliance on energy metabolism restricted to glycolysis, which is specific to the premineralizing skeletal cells, was tested as a selectable marker for cells in this stage. Day 12 alkaline phosphatase (ALP) and day 20-21 calcium precipitates were used as early and late OPC differentiation markers. Malonate, a competitive inhibitor of succinate dehydrogenase, was added to the OPC stimulation medium, to interfere with the Krebs cycle-dependent energy metabolism operating in most of the stromal cells. OPCs that entered the stage of energy metabolism restricted to glycolysis were expected to become malonate resistant. Malonate showed dose and time dependence, 10 mM malonate added on day 3, decreased day 12 ALP activity/well to the lowest level. Variations in time and length of exposure to malonate used during the first 12 days of differentiation showed an inverse correlation between specific ALP activity and cell yield. Malonate-treated variations of specific ALP and of cell yield indices were up to 30- to 40-fold larger than variations within day 21 calcium precipitates. Thus, calcifying cells were almost unchanged relatively to noncalcifying cells. These results indicate that malonate-resistant cells are mostly selected, rather than induced, to differentiate by malonate. The results also show that stromal derived OPCs undergo a similar biochemical stage as in chondrocytes.

Use of dual-energy X-ray absorptiometry (DEXA) to follow mineral content changes in small ceramic implants in rats

Dual energy X-ray absorptiometry (DEXA) imaging was used to quantify bone ingrowth into hydroxyapatite (HA) ceramic implants in rats. HA cylinders implanted in the proximal tibiae were followed for 13 wk. The increase in alkaline phosphatase (ALP) activity within the implants preceded the increase in mineral content as measured non-invasively by the DEXA technique. This was consistent with the timing of ALP activity in respect of mineralization as they occur during fracture healing. The results show that DEXA imaging is useful in measuring bone ingrowth into small ceramic HA implants in vivo, despite the high mineral content background of the implant scaffold.

Expression of genes containing the IgH enhancer in non-lymphoid cells

Nuclear run-on experiments were used to verify the hypothesis that extinction of expression of Ig synthesis in L cell x myeloma hybrids occurs at the transcriptional level. Both the H chain enhancer and promoter have been shown to be the targets for extinction in myeloma x T cell hybrids. To examine the expression of genes containing the immunoglobulin heavy chain gene (IgH) enhancer in stably transfected non-B cells, we used a vector with two selectable markers, one of which (gpt providing resistance to mycophenolic acid) either lacks an enhancer or contains the IgH enhancer, the other (neo providing resistance to G418) contains an SV40 enhancer. Stable transfectants of both myeloma (J558L) and L cells selected using G418 were tested to determine if they are also mycophenolic acid resistant. When the IgH enhancer is positioned 3' to the gpt gene, transfected J558L are mycophenolic acid resistant whereas stably transfected L-cells are mycophenolic acid sensitive. However, when large numbers of L cell transfectants are exposed to mycophenolic acid for a prolonged period, resistant subclones emerge. When the 700-bp IgH enhancer fragment was used, the majority of the subclones examined had amplified the vector, between 3 and 38 copies; when a 400-bp subfragment was used no change in the integrated genes was seen. In both cases, in the mycophenolic acid resistant subclones, increased accumulation of gpt and neo mRNA is seen. However, the gpt specific transcripts are heterogeneous in size whereas the neo transcripts are of a discrete size. The heterogeneity of the gpt transcripts results at least in part from heterogeneous initiation. When HXM-resistant L cell subclones are fused to the gamm 2b, k myeloma 4T001, extinction of Ig production occurs; therefore these cells are still capable of negatively regulating Ig expression. These results are discussed from the standpoint of both cis and trans regulatory elements and factors in non-lymphoid cells.

Self-reactive delayed type hypersensitivity induced in mice by syngeneic lymphoblasts. II. Isolation of two distinct lymphoblast antigens, one of which reacts (or cross-reacts) with anti-H-2Dd monoclonal antibody

X-irradiated (250 rad) or normal A mice injected with syngeneic concanavalin A-induced lymphoblasts (syn-Con A blasts) developed an inflammatory response in their footpads 24 to 72 h after injection of syngeneic lipopolysaccharide-induced lymphoblasts (syn-LPS blasts) into these tissues. This immunological activity was designated syngeneic delayed type hypersensitivity (syn-DTH), because T cells transferred the response to naive recipients. Analysis on Ultrogel or Sephadex G-50 columns revealed that a Con A-blast extract contains two syn-DTH-stimulating antigens: a small antigen (6000-7000) and a large antigen (apparent MW of 160,000-175,000). This conclusion held true even when protease inhibitors were included in the fractionation procedure. The approximate molecular weights of these antigens estimated by the gel filtrations were confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The large lymphoblast syn-DTH-stimulating antigen contains carbohydrate residues but not products of the H-2 genetic region. The small antigen does not contain sugar moieties, but it expresses affinity to anti-H-2Dd monoclonal antibody. The immune response to the small antigen but not to the large antigen is genetically restricted at both the induction and the elicitation phases of the DTH. A strain of mice immunized with the small antigen generated syn-DTH after challenge with lymphoblasts of B10.T (6R) mice, which share the H-2Dd subregion with A mice but not the H-2K or the H-2I subregions. Fast protein liquid chromatography of the small antigen yielded a purified material which appeared as a single band after Coomassie staining of its gel electrophoresis.