A Novel Approach to Negative Pressure Wound Therapy: Use of High Suction Capillary Device to Improve Wound Healing

INTRODUCTION

Negative Pressure Wound Therapy (NPWT) is a procedure used for nonhealing wounds. In NPWT, a special sealed dressing of large cell foam (>400 µm) or gauze is connected to a pump. Most commonly, negative pressures between -10 and -125 millimeters of mercury (mm Hg) are used. The mechanism of healing is unknown but maybe attributable to removal of the exudate and bacteria, and the stimulation of tissue repair through microdeformation. Reticulated foams with micron-size open cells, Capillary Suction Devices (CSD; 100 to 5 µm) exert capillary suction between 10 and 70 mm of Hg with a multilayered foam dressing.

MATERIALS AND METHODS

Yorkshire pigs received 5 surgical excision wounds, 3 cm2, on each side of the back. The wounds were covered with a NPWT dressing (110 mm Hg negative pressure by a pump), CSD with capillary suctions of 30 mm Hg (CSD-30) and 70 mm Hg (CSD-70), and a conventional gauze dressing. The wounds were measured on day 2, and then every 4-5 days thereafter; the total fluid collected by the various dressing over time.

RESULTS

By post-wound day 20, the wounds treated with CSD-70 and NPWT were 100% closed while the wounds treated with CSD-30 and gauze were 65% and 45%, respectively. This indicated comparable wound closure efficacies for CSD-70 and NPWT. The average total fluid uptake measured in grams dry weight were similar for CSD-70 and NPWT, 36 and 38 g, respectively, while the values were 24 g for CSD-30 and 12 g for gauze. However, the maximum fluid uptake observed at day 2 indicated that CSD-70 and CSD 30, 24 and 14 g, respectively, were superior to NPWT and gauze 12 and 7 g, respectively.

CONCLUSION

This data indicate comparable wound closure efficacies for CSD-70 and NPWT. It is felt that CSD is an effective, safe, and lower cost alternative to vacuum-assisted NPWT.

The burn wound inflammatory response is influenced by midazolam

Burn patients requiring hospitalization are often treated for anxiety with benzodiazepines (BDZs). Benzodiazepines are reported to influence immune system function. Immune system alterations are a major cause of burn-induced mortality. We wanted to determine whether the BDZ, midazolam given daily at an anxiolytic dose, had any influence on the burn injury-induced inflammatory response in the blood and wound. Mice received a 15% total body surface area flame burn and received either midazolam 1 mg/kg i.p. or saline 0.1 ml daily. Blood and skin wounds were harvested 24 h after injection on post-burn day 2, 3, 7, or 8. Mice treated with midazolam had significantly lower serum IL-1β (p=0.002), TNF-α (p=0.002), IL-6 (p=0.016), IL-10 (p=0.009), and TGF-β (p=0.004) than saline-treated mice, with little impact on serum chemokine levels. In the wound, TNF-α and IL-10 were the only cytokines significantly influenced by the drug, being lower (p=0.018) and higher (p=0.006), respectively. The chemokines in the wound influenced significantly by midazolam were MIP-1α, MIP-1β, and MIP-2 while MCP-1 and KC were not. There were more inflammatory cells at the burn wound margin in midazolam-treated mice on post-burn day 3. Although serum nitrate/nitrite was significantly increased by midazolam (p=0.03), both eNOS and iNOS mRNA expression in the wound were similar to the saline group. We found that midazolam given daily after burn injury significantly influenced the inflammatory response. The clinical implications of these findings on wound healing and shock following burn injury, especially larger burns, deserve further investigation.

The abundance of Rad51 protein in mouse embryonic stem cells is regulated at multiple levels

DNA double-strand breaks (DSBs) in embryonic stem (ES) cells are repaired primarily by homologous recombination (HR). The mechanism by which HR is regulated in these cells, however, remains enigmatic. To gain insight into such regulatory mechanisms, we have asked how protein levels of Rad51, a key component of HR, are controlled in mouse ES cells and mouse embryo fibroblasts (MEFs). The Rad51 protein level is about 15-fold higher in ES cells than in MEFs. The level of Rad51 mRNA, however, is only ~2-fold higher, indicating that the differences in mRNA levels due to rates of transcription or mRNA stability are not sufficient to account for the large difference in the abundance of Rad51 protein. Comparison of Rad51 half-lives between ES cells and MEFs also did not explain the elevated level of Rad51 protein in the ES cells. A comparative assessment of the Rad51 translation level demonstrated that it is translated with much greater efficacy in ES cells than in MEFs. To determine whether this high level of translation in ES cells is a general phenomenon in these cells or whether it is a characteristic of specific proteins, such as those involved with recombination and cell cycle progression, we compared mechanisms that regulate the level of Pcna in ES cells with those that regulate Rad51. The half-life of Pcna and its rate of synthesis were considerably different from those of Rad51 in ES cells, demonstrating that regulation of Rad51 abundance cannot be generalized to other ES cell proteins and not to proteins involved in DNA replication and cell cycle control. Finally, we show that only a small proportion of the abundant Rad51 protein population is activated under basal conditions in ES cells and recruited to DNA DSBs and/or stalled replication forks.

The human DEK oncogene regulates DNA damage response signaling and repair

The human DEK gene is frequently overexpressed and sometimes amplified in human cancer. Consistent with oncogenic functions, Dek knockout mice are partially resistant to chemically induced papilloma formation. Additionally, DEK knockdown in vitro sensitizes cancer cells to DNA damaging agents and induces cell death via p53-dependent and -independent mechanisms. Here we report that DEK is important for DNA double-strand break repair. DEK depletion in human cancer cell lines and xenografts was sufficient to induce a DNA damage response as assessed by detection of γH2AX and FANCD2. Phosphorylation of H2AX was accompanied by contrasting activation and suppression, respectively, of the ATM and DNA-PK pathways. Similar DNA damage responses were observed in primary Dek knockout mouse embryonic fibroblasts (MEFs), along with increased levels of DNA damage and exaggerated induction of senescence in response to genotoxic stress. Importantly, Dek knockout MEFs exhibited distinct defects in non-homologous end joining (NHEJ) when compared to their wild-type counterparts. Taken together, the data demonstrate new molecular links between DEK and DNA damage response signaling pathways, and suggest that DEK contributes to DNA repair.

Mouse embryonic stem cells, but not somatic cells, predominantly use homologous recombination to repair double-strand DNA breaks

Embryonic stem (ES) cells give rise to all cell types of an organism. Since mutations at this embryonic stage would affect all cells and be detrimental to the overall health of an organism, robust mechanisms must exist to ensure that genomic integrity is maintained. To test this proposition, we compared the capacity of murine ES cells to repair DNA double-strand breaks with that of differentiated cells. Of the 2 major pathways that repair double-strand breaks, error-prone nonhomologous end joining (NHEJ) predominated in mouse embryonic fibroblasts, whereas the high fidelity homologous recombinational repair (HRR) predominated in ES cells. Microhomology-mediated end joining, an emerging repair pathway, persisted at low levels in all cell types examined. The levels of proteins involved in HRR and microhomology-mediated end joining were highly elevated in ES cells compared with mouse embryonic fibroblasts, whereas those for NHEJ were quite variable, with DNA Ligase IV expression low in ES cells. The half-life of DNA Ligase IV protein was also low in ES cells. Attempts to increase the abundance of DNA Ligase IV protein by overexpression or inhibition of its degradation, and thereby elevate NHEJ in ES cells, were unsuccessful. When ES cells were induced to differentiate, however, the level of DNA Ligase IV protein increased, as did the capacity to repair by NHEJ. The data suggest that preferential use of HRR rather than NHEJ may lend ES cells an additional layer of genomic protection and that the limited levels of DNA Ligase IV may account for the low level of NHEJ activity.

Generation of mice with a conditional allele for transforming growth factor beta 1 gene

Transforming growth factor beta1 (TGFbeta1) is a multifunctional growth factor involved in wound healing, tissue fibrosis, and in the pathogenesis of many syndromic diseases (e.g., Marfan syndrome, Camurati-Engelmann disease) and muscular, neurological, ophthalmic, cardiovascular and immunological disorders, and cancer. Since the generation of Tgfb1 knockout mice, there has been extraordinary progress in understanding its physiological and pathophysiological function. Here, we report the generation of a conditional knockout allele for Tgfb1 in which its exon 6 is flanked with LoxP sites. As proof of principle, we crossed these mice to LckCre transgenic mice and specifically disrupted Tgfb1 in T cells. The results indicate that T-cell-produced TGFbeta1 is required for normal in vivo regulation of peripheral T-cell activation, maintenance of T-cell homeostasis, and suppression of autoimmunity.

Employing a recombinant HLA-DR3 expression system to dissect major histocompatibility complex II-thyroglobulin peptide dynamism: a genetic, biochemical, and reverse immunological perspective

Previously, we have shown that statistical synergism between amino acid variants in thyroglobulin (Tg) and specific HLA-DR3 pocket sequence signatures conferred a high risk for autoimmune thyroid disease (AITD). Therefore, we hypothesized that this statistical synergism mirrors a biochemical interaction between Tg peptides and HLA-DR3, which is key to the pathoetiology of AITD. To test this hypothesis, we designed a recombinant HLA-DR3 expression system that was used to express HLA-DR molecules harboring either AITD susceptibility or resistance DR pocket sequences. Next, we biochemically generated the potential Tg peptidic repertoire available to HLA-DR3 by separately treating 20 purified human thyroglobulin samples with cathepsins B, D, or L, lysosomal proteases that are involved in antigen processing and thyroid biology. Sequences of the cathepsin-generated peptides were then determined by matrix-assisted laser desorption ionization time-of-flight-mass spectroscopy, and algorithmic means were employed to identify putative AITD-susceptible HLA-DR3 binders. From four predicted peptides, we identified two novel peptides that bound strongly and specifically to both recombinant AITD-susceptible HLA-DR3 protein and HLA-DR3 molecules expressed on stably transfected cells. Intriguingly, the HLA-DR3-binding peptides we identified had a marked preference for the AITD-susceptibility DR signatures and not to those signatures that were AITD-protective. Structural analyses demonstrated the profound influence that the pocket signatures have on the interaction of HLA-DR molecules with Tg peptides. Our study suggests that interactions between Tg and discrete HLA-DR pocket signatures contribute to the initiation of AITD.

Calcineurin deficiency decreases inflammatory lesions in transforming growth factor beta1-deficient mice

Transforming growth factor (TGF) beta1) is an immunoregulatory cytokine involved in self-tolerance and lymphocyte homeostasis. Tgfb1 knock-out (KO) mice develop severe multi-focal autoimmune inflammatory lesions due to [Ca(2+)]i deregulation in T cells, and die within 3 weeks after birth. Because the calcineurin inhibitor FK506 inhibits the hyperresponsiveness of Tgfb1(-/-) thymocytes, and because calcineurin Abeta (CNAbeta)-deficient mice do not reject allogenic tumours, we have generated Tgfb1(-/-) Cnab(-/-) mice to address whether CNAbeta deficiency prevents T cell activation and inflammation in Tgfb1(-/-) mice. Here we show that in Tgfb1(-/-) Cnab(-/-) mice inflammation is reduced significantly relative to that in Tgfb1(-/-) mice. However, both CD4(+) and CD8(+) T cells in double knock-out (DKO) mice are activated, as revealed by up-regulation of CD11a lymphocyte function-associated antigen-1 (LFA-1), CD44 and CD69 and down-regulation of CD62L. These data suggest that deficiency of CNAbeta decreases inflammatory lesions but does not prevent activation of autoreactive T cells. Also Tgfb1(-/-) T cells can undergo activation in the absence of CNAbeta, probably by using the other isoform of calcineurin (CNAalpha) in a compensatory manner. CNAbeta-deficient T cells undergo spontaneous activation in vivo and are activated upon anti-T cell receptor stimulation in vitro. Understanding the role of calcineurin in T cell regulation should open up new therapeutic opportunities for inflammation and cancer.

The effects of HSP72 expression on adhesion receptor activation and phagolysosome function in human PMNs (134.93)

Heat shock protein 72 (HSP72) expression is a hallmark of functionally suppressed neutrophils from pediatric burn patients. CD11b and CD15 are critical receptors that mediate neutrophil (PMN) adhesion. In this study, we examined the effects of HSP72 on these receptors as well as phagolysosome function. Expression of CD11b, CD15 and pHrodo were measured by flow cytometry. HSP72 expression in PMNs, induced by 60-90 min incubation at 42C, suppressed the upregulation of high affinity CD11b conformation induced by fMLP (~90% reduction vs controls). Additionally, CD15 expression is reduced in HSP72 positive PMNs. GM-CSF treatment (5-25 ng/ml) appears to have a modest ability to preserve PMN function in stressed PMNs. HSP72 positive PMNs also have a reduced capacity phagocytose. Opsonized pHrodo labelled Staphylococcus aureus were incubated with HSP72 positive or negative PMNs. Control samples had significantly more pHrodo positive bacteria (~2-fold increase, controls vs stressed PMNs, P<0.01) than the thermally stressed cells. However, the HSP72 positive PMNs appeared to acidify phagolysosomes to the same extent as control PMNs. Taken together, these data suggest that HSP72 expression reduces adhesion as well as the extent of phagocytosis. These deficits may contribute to the immune suppression found in thermally injured patients. Supported by Shriners of North America.

Absence of nucleolar disruption after impairment of 40S ribosome biogenesis reveals an rpL11-translation-dependent mechanism of p53 induction

Impaired ribosome biogenesis is attributed to nucleolar disruption and diffusion of a subset of 60S ribosomal proteins, particularly ribosomal protein (rp)L11, into the nucleoplasm, where they inhibit MDM2, leading to p53 induction and cell-cycle arrest. Previously, we demonstrated that deletion of the 40S rpS6 gene in mouse liver prevents hepatocytes from re-entering the cell cycle after partial hepatectomy. Here, we show that this response leads to an increase in p53, which is recapitulated in culture by rpS6-siRNA treatment and rescued by the simultaneous depletion of p53. However, disruption of biogenesis of 40S ribosomes had no effect on nucleolar integrity, although p53 induction was mediated by rpL11, leading to the finding that the cell selectively upregulates the translation of mRNAs with a polypyrimidine tract at their 5'-transcriptional start site (5'-TOP mRNAs), including that encoding rpL11, on impairment of 40S ribosome biogenesis. Increased 5'-TOP mRNA translation takes place despite continued 60S ribosome biogenesis and a decrease in global translation. Thus, in proliferative human disorders involving hypomorphic mutations in 40S ribosomal proteins, specific targeting of rpL11 upregulation would spare other stress pathways that mediate the potential benefits of p53 induction.

Intracellular cytokines

The principal technique described in this unit was developed for detecting cytokines produced by T cells, specifically interferon gamma (IFN-gamma) and interleukin 4 (IL-4). In addition to providing information about which cytokines are being produced, it also helps to phenotypically identify the specific cells producing them. For example, CD4(+) or CD8(+) cells can be subdivided into T(H)1/T(H)2 helper cells or T(C)1/T(C)2 suppressor cells, respectively. This procedure can be useful in examining the response of cells to a variety of agonists, the immune function in various disease states, and the level of lymphocyte activation or suppression. In addition, it can be used to detect a variety of cytokines in many cell types, although the methodology must be carefully evaluated for each cytokine or cell type of interest. Additional methods are included for the stimulation of T cells with allogeneic cells and for the performance of controls for labeling specificity.

Orchestration of the S-phase and DNA damage checkpoint pathways by replication forks from early origins

The S-phase checkpoint activated at replication forks coordinates DNA replication when forks stall because of DNA damage or low deoxyribonucleotide triphosphate pools. We explore the involvement of replication forks in coordinating the S-phase checkpoint using dun1Delta cells that have a defect in the number of stalled forks formed from early origins and are dependent on the DNA damage Chk1p pathway for survival when replication is stalled. We show that providing additional origins activated in early S phase and establishing a paused fork at a replication fork pause site restores S-phase checkpoint signaling to chk1Delta dun1Delta cells and relieves the reliance on the DNA damage checkpoint pathway. Origin licensing and activation are controlled by the cyclin-Cdk complexes. Thus, oncogene-mediated deregulation of cyclins in the early stages of cancer development could contribute to genomic instability through a deficiency in the forks required to establish the S-phase checkpoint.

TGFbeta1 deficiency does not affect the generation and maintenance of CD4+CD25+FOXP3+ putative Treg cells, but causes their numerical inadequacy and loss of regulatory function

TGFbeta1 is considered to be required for peripheral maintenance of CD4(+)CD25(+)FOXP3(+) T(reg) cells. However, we demonstrate no reduction in the percentage of such T cells in the spleens and thymi of Tgfb1(-/-) mice. Although putative T(reg) cells, characterized as CD4(+)CD25(+)FOXP3(+)CD62L(+) T cells, are increased in Tgfb1(-/-) mice, they may be inadequate to control activated T cells since the ratio of activated T cells:putative T(reg) cells is several-fold higher in Tgfb1(-/-) mice than in control mice. We further show that whereas Tgfb1(-/-) mice that express a chicken OVA-specific TCR transgene (DO11.10) have an increase in putative T(reg) cells, there are no detectable CD4(+)CD25(+) T cells in the spleens of DO11.10 Rag1(-/-) mice suggesting that T(reg)-cell generation is self-antigen dependent regardless of whether they express Tgfb1. Finally, we demonstrate that Tgfb1(-/-) T cells remain responsive to the suppressive effect of TGFbeta1 in vitro. These data suggest that TGFbeta1 is required for the regulatory function of T(reg) cells to prevent activation of T cells and autoimmunity.

Loss of the retinoblastoma tumor suppressor: differential action on transcriptional programs related to cell cycle control and immune function

Functional inactivation of the retinoblastoma tumor suppressor gene product (RB) is a common event in human cancers. Classically, RB functions to constrain cellular proliferation, and loss of RB is proposed to facilitate the hyperplastic proliferation associated with tumorigenesis. To understand the repertoire of regulatory processes governed by RB, two models of RB loss were utilized to perform microarray analysis. In murine embryonic fibroblasts harboring germline loss of RB, there was a striking deregulation of gene expression, wherein distinct biological pathways were altered. Specifically, genes involved in cell cycle control and classically associated with E2F-dependent gene regulation were upregulated via RB loss. In contrast, a program of gene expression associated with immune function and response to pathogens was significantly downregulated with the loss of RB. To determine the specific influence of RB loss during a defined period and without the possibility of developmental compensation as occurs in embryonic fibroblasts, a second system was employed wherein Rb was acutely knocked out in adult fibroblasts. This model confirmed the distinct regulation of cell cycle and immune modulatory genes through RB loss. Analyses of cis-elements supported the hypothesis that the majority of those genes upregulated with RB loss are regulated via the E2F family of transcription factors. In contrast, those genes whose expression was reduced with the loss of RB harbored different promoter elements. Consistent with these analyses, we found that disruption of E2F-binding function of RB was associated with the upregulation of gene expression. In contrast, cells harboring an RB mutant protein (RB-750F) that retains E2F-binding activity, but is specifically deficient in the association with LXCXE-containing proteins, failed to upregulate these same target genes. However, downregulation of genes involved in immune function was readily observed with disruption of the LXCXE-binding function of RB. Thus, these studies demonstrate that RB plays a significant role in both the positive and negative regulations of transcriptional programs and indicate that loss of RB has distinct biological effects related to both cell cycle control and immune function.

Modulation of apoptosis and the production of reactive oxygen species in human neutrophils with epigallocatechin-3-gallate (EGCG) (101.6)

Our laboratory has demonstrated that following thermal injury, neutrophils (PMNs) display altered immune responsiveness. Decreased apoptosis was associated with the expression of Heat Shock Protein 72 (HSP72), while increased apoptosis is associated with the production of reactive oxygen species. EGCG is an anti-oxidant found in green tea which possesses immunomodulatory properties. In this study, we investigated the effects of EGCG on PMN apoptosis and the production of reaction oxygen species. Human PMNs (HSP 72 + or −) were treated with tumor necrosis factor (TNF[alpha]) or phorbol myristate acetate (PMA), with or without EGCG. PMNs were analyzed for apoptosis, the production of superoxide anion (O2−), and hydrogen peroxide (H2O2). PMNs treated with EGCG had a significant reduction in the percentage of cells undergoing apoptosis with either agonist (by 78 and 53%, respectively). While PMNs expressing HSP72 had decreased apoptosis compared to controls, treatment with EGCG further decreased the percentage of HSP 72+ PMNs undergoing apoptosis. Treatment with EGCG significantly reduced the production of H2O2 and O2− by PMNs treated with TNF[alpha]or PMA. The data suggests that EGCG significantly reduces apoptosis, H2O2 and O2− in activated PMNs. Due to its low toxicity, ECGC may be an ideal agent to modulate the inflammatory response associated with burn injury.

Supported in part by a grant from Shriners of North America

TGFbeta1 is not essential for generation and maintenance of natural Treg cells (128.10)

Natural CD4+CD25+FOXP3+ Treg cells serve as powerful regulators of autoimmunity. Hence, there has been a great deal of interest in understanding their regulation. TGFβ1 is considered to be required for peripheral maintenance of Treg cells. However, we demonstrate an increase in the percentage of FOXP3+ Treg cells in the spleens and thymi of Tgfb1−/− mice. Despite this abundance of Treg cells, Tgfb1−/− mice develop a marked expansion of activated T cells in their lymphoid organs, suggesting that activated Tgfb1−/− T cells may not be amenable to suppression any more. However, we demonstrate that Tgfb1−/− T cells do remain responsive to the suppressive effect of TGFβ1 in vitro, suggesting that the absence of TGFβ1 production by Treg cells likely leads to their loss of regulatory function. Finally, we show that whereas Tgfb1−/− mice that express a chicken OVA-specific TCR transgene (DO11.10) have an increase in Treg cells, there are no detectable CD4+CD25+ T cells in the spleens of DO11.10 Rag1−/− mice that have no self-reactive T-cells, regardless of whether they express Tgfb1. This suggests that Treg-cell generation is self-antigen dependent and that TGFβ1 is not required for Treg-cell generation and maintenance. We contemplate that TGFβ1 is likely required for the regulatory function of Treg cells to prevent activation of T cells and autoimmunity.

Stress and prolactin effects on bone marrow myeloid cells, serum chemokine and serum glucocorticoid levels in mice

OBJECTIVE

Current evidence supports the conclusion that prolactin (PRL) is not an obligate immunoregulatory hormone and influences the immune system predominantly during stress conditions. In this study, we examined the impact of PRL on the psychogenic stress-induced responses of myeloid cells.

METHODS

Seven-week-old PRL+/- (normal) and PRL-/- (deficient) mice were exposed to a predator for 1 h/day on 3 consecutive days. Another group of PRL-deficient mice received either 1 pituitary graft (hyperprolactinemic) or sham surgery at 5 weeks of age, while PRL-normal mice only received sham surgery. Two weeks later, these mice were also subjected to predator exposure. One day after the last predator exposure session, all mice were killed and the bone marrow and blood harvested.

RESULTS

Significant differences in the myeloid cells between PRL-normal and PRL-deficient mice only occurred in stressed conditions. The median serum corticosterone levels were consistently higher in PRL-deficient mice. The implantation of a pituitary graft lowered the corticosterone levels to those observed in PRL-normal mice. The absolute number of immature neutrophils as well as the numbers of granulocyte macrophage, monocyte/macrophage and granulocyte colonies were significantly higher in the stressed PRL-deficient mice; however, only the increased number of immature neutrophils was reversed by pituitary grafting.

CONCLUSIONS

Our findings support previous observations that PRL influences myeloid cells of the bone marrow most profoundly in stressed conditions. However, the mechanism by which PRL influences bone marrow myeloid cells during stress cannot be explained solely by its effect on serum corticosterone.

Bisphenol A facilitates bypass of androgen ablation therapy in prostate cancer

Prostatic adenocarcinomas depend on androgen for growth and survival. First line treatment of disseminated disease exploits this dependence by specifically targeting androgen receptor function. Clinical evidence has shown that androgen receptor is reactivated in recurrent tumors despite the continuance of androgen deprivation therapy. Several factors have been shown to restore androgen receptor activity under these conditions, including somatic mutation of the androgen receptor ligand-binding domain. We have shown previously that select tumor-derived mutants of the androgen receptor are receptive to activation by bisphenol A (BPA), an endocrine-disrupting compound that is leached from polycarbonate plastics and epoxy resins into the human food supply. Moreover, we have shown that BPA can promote cell cycle progression in cultured prostate cancer cells under conditions of androgen deprivation. Here, we challenged the effect of BPA on the therapeutic response in a xenograft model system of prostate cancer containing the endogenous BPA-responsive AR-T877A mutant protein. We show that after androgen deprivation, BPA enhanced both cellular proliferation rates and tumor growth. These effects were mediated, at least in part, through androgen receptor activity, as prostate-specific antigen levels rose with accelerated kinetics in BPA-exposed animals. Thus, at levels relevant to human exposure, BPA can modulate tumor cell growth and advance biochemical recurrence in tumors expressing the AR-T877A mutation.

Self-antigen recognition by TGF beta1-deficient T cells causes their activation and systemic inflammation

To investigate whether the multifocal inflammatory disease in TGFbeta1-deficient mice is caused by self-antigen (self-Ag)-specific autoreactive T cells, or whether it is caused by antigen independent, spontaneous hyperactivation of T cells, we have generated Tgfb1(-/-) and Tgfb1(-/-) Rag1(-/-) mice expressing the chicken OVA-specific TCR transgene (DO11.10). On a Rag1-sufficient background, Tgfb1(-/-) DO11.10 mice develop a milder inflammation than do Tgfb1(-/-) mice, and their T cells display a less activated phenotype. The lower level of activation correlates with the expression of hybrid TCR (transgenic TCRbeta and endogenous TCRalpha), which could recognize self-Ag and undergo activation. In the complete absence of self-Ag recognition (Tgfb1(-/-) DO11.10 Rag1(-/-) mice) inflammation and T-cell activation are eliminated, demonstrating that self-Ag recognition is required for the hyper-responsiveness of TGFbeta1-deficient T cells. Thus, TGFbeta1 is required for the prevention of autoimmune disease through its ability to control the activation of autoreactive T cells to self-Ag.

Liver-Specific pRB Loss Results in Ectopic Cell Cycle Entry and Aberrant Ploidy

The liver exhibits an exquisitely controlled cell cycle, wherein hepatocytes are maintained in quiescence until stimulated to proliferate. The retinoblastoma tumor suppressor, pRB, plays a central role in proliferative control by inhibiting inappropriate cell cycle entry. In many cases, liver cancer arises due to aberrant cycles of proliferation, and correspondingly, pRB is functionally inactivated in the majority of hepatocellular carcinomas. Therefore, to determine how pRB loss may provide conditions permissive for deregulated hepatocyte proliferation, we investigated the consequence of somatic pRB inactivation in murine liver. We show that liver-specific pRB loss results in E2F target gene deregulation and elevated cell cycle progression during post-natal growth. However, in adult livers, E2F targets are repressed and hepatocytes become quiescent independent of pRB, suggesting that other factors may compensate for pRB loss. Therefore, to probe the consequences of acute pRB inactivation in livers of adult mice, we gave adenoviral-Cre by i.v. injection. We show that acute pRB loss is sufficient to elicit E2F target gene expression and cell cycle entry in adult liver, demonstrating a critical role for pRB in maintaining hepatocyte quiescence. Finally, we show that liver-specific pRB loss results in the development of nuclear pleomorphism associated with elevated ploidy that is evident in adult mice harboring both acute and chronic pRB loss. Together, these results show the crucial role played by pRB in maintaining hepatocyte quiescence and ploidy in adult liver in vivo and underscore the critical importance of delineating the consequences of acute pRB loss in adult animals.

Unconjugated bilirubin inhibits VCAM-1-mediated transendothelial leukocyte migration

During lymphocyte migration, engagement of VCAM-1 stimulates the generation of endothelial cell-derived reactive oxygen species (ROS) and activation of matrix metalloproteinases, facilitating endothelial retraction. Because bilirubin is a potent antioxidant, we examined the hypothesis that this bile pigment inhibits VCAM-1-dependent cellular events. The migration of isolated murine splenic lymphocytes across monolayers of murine endothelial cell lines (which constitutively express VCAM-1) is significantly inhibited by physiological concentrations of bilirubin, in the absence of an effect on lymphocyte adhesion. Bilirubin administration also suppresses VCAM-1-stimulated ROS generation and reduces endothelial cell matrix metalloproteinase activity. In a murine asthma model characterized by VCAM-1-dependent airway inflammation, treatment of C57BL6/J mice with i.p. bilirubin decreases the total leukocyte count in the lung parenchyma and lavage fluid, through specific inhibition of eosinophil and lymphocyte infiltration. Blood eosinophil counts were increased in bilirubin-treated animals, while VCAM-1 expression in the capillary endothelium and cytokine levels in both lung lavage and supernatants from cultured lymph node lymphocytes were unchanged, suggesting that bilirubin inhibits leukocyte migration.

CONCLUSION

bilirubin blocks VCAM-1-dependent lymphocyte migration in vitro and ameliorates VCAM-1-mediated airway inflammation in vivo, apparently through the suppression of cellular ROS production. These findings support a potential role for bilirubin as an endogenous immunomodulatory agent.

Elimination of both CD4+ and CD8+ T cells but not B cells eliminates inflammation and prolongs the survival of TGFbeta1-deficient mice

Transforming growth factor beta1 (TGFbeta1) is a potent negative immunoregulatory molecule. We have previously shown that the autoimmune-mediated weaning-age lethality of Tgfb1-/- mice is reversed upon genetic combination with Scid or Rag null alleles. Here, we show that elimination of T but not B cells is sufficient for the reversal, but elimination of either CD4+ or CD8+ cells is not. Although elimination of B cells does not rescue TGFbeta1-deficient animals from autoimmunity, B cells are hyperresponsive to LPS in the absence of TGFbeta1. TGFbeta1 deficiency leads to activation of CD8+ T cells as suggested by down-modulation of CD8 even in the absence of CD4+ T cells. This study provides evidence that both CD4+ and CD8+ T cells, but not B cells, have the ability to cause inflammation in the absence of TGFbeta1. However, though TGFbeta1-deficient B cells are hyperresponsive to stimulation, alone they are not sufficient to cause inflammation.

Unconjugated bilirubin induces apoptosis in colon cancer cells by triggering mitochondrial depolarization

Bilirubin is the principal end product of heme degradation. Prompted by epidemiologic analyses demonstrating an inverse correlation between serum bilirubin levels and cancer mortality, we examined the effect(s) of bilirubin on the growth and survival of colon adenocarcinoma cells. Adenocarcinoma cell monolayers were treated with bilirubin over a range of bilirubin:BSA molar ratios (0-0.6), and viability was assessed colorimetrically. Apoptosis was characterized by TUNEL assay, annexin V staining and caspase-3 activation. The mechanism(s) by which bilirubin induces apoptosis was investigated by Western blotting for cytochrome c release, assaying for caspase-8 and caspase-9 activation and for mitochondrial depolarization by JC-1 staining. The direct effect of bilirubin on the membrane potential of isolated mitochondria was evaluated using light-scattering and fluorescence techniques. Bilirubin decreased the viability of all colon cancer cell lines tested in a dose-dependent manner. Cells exhibited substantial apoptosis when exposed to bilirubin concentrations ranging 0-50 microM, as demonstrated by an 8- to 10-fold increase in TUNEL and annexin V staining and in caspase-3 activity. Bilirubin treatment evokes specific activation of caspase-9, enhances cytochrome c release into the cytoplasm and triggers the mitochondrial permeability transition in colon cancer monolayers. Additionally, bilirubin directly induces the depolarization of isolated rat liver mitochondria, an effect that is not inhibited by cyclosporin A. Bilirubin stimulates apoptosis of colon adenocarcinoma cells in vitro through activation of the mitochondrial pathway, apparently by directly dissipating mitochondrial membrane potential. As this effect is triggered at concentrations normally present in the intestinal lumen, we postulate a physiologic role for bilirubin in modulating colon tumorigenesis.

Effects of prolactin level on burn-induced aberrations in myelopoiesis

In this study, we sought to determine if prolactin (PRL) had any influence on burn-induced alterations in myelopoiesis and serum IL-6, IL-10, IL-12, IFN-gamma, TNF-alpha, and MCP-1 levels. To do this, we used mice that were PRL normal, PRL deficient, or hyperprolactinemic and had received a 15% total body surface area burn, sham treatment, or no treatment. We performed clonogenic assays of bone marrow cells, and we found that sham treatment significantly decreased monocyte/macrophage (M) colony formation relative to the control group in the PRL-deficient and PRL-normal mice (P < 0.01). Hyperprolactinemia attenuated the sham-induced decrease in M colony formation. Burn injury significantly increased M colony formation relative to the sham group with an equal significance in the PRL-deficient and PRL-normal mice (P < 0.05). We also showed that burn led to a significant increase in GM colony formation relative to the sham group. This burn-induced increase was significant in the PRL-normal (P < 0.05) and the PRL-deficient (P < 0.01) mice. In the PRL-normal mice, burn injury caused a 2.1-fold increase in the GM colony number, whereas in the PRL-deficient mice burn led to a 2.6-fold increase in GM colony number. When comparing the effects of burn injury on colony formation to the control groups, there were no significant differences seen, irrespective of the PRL level. We observed that all of the cytokines studied, with the exception of IL-10, were influenced by either sham treatment, burn injury, or both forms of stress. This stress-induced response occurred most often in animals that were either hypo- or hyperprolactinemic. We conclude that the PRL level was able to influence the sham-induced and burn-induced alterations in GM and M colony formation. Under euprolactinemic conditions, mice exhibited less often with stress-induced serum cytokine level alterations. We did not find any significant correlations with any of the serum cytokine levels and the ability to form colonies. Importantly, the sham treatment led to immune alterations independent of, and sometimes opposite of burn-induced effects.

TGF-beta 1 regulates lymphocyte homeostasis by preventing activation and subsequent apoptosis of peripheral lymphocytes

TGF-beta1 plays an important role in the maintenance of immune homeostasis and self-tolerance. To determine the mechanism by which TGF-beta1 prevents autoimmunity we have analyzed T cell activation in splenic lymphocytes from TGF-beta1-deficient mice. Here we demonstrate that unlike wild-type splenic lymphocytes, those from Tgfb1(-/-) mice are hyporesponsive to receptor-mediated mitogenic stimulation, as evidenced by diminished proliferation and reduced IL-2 production. However, they have elevated levels of IFN-gamma and eventually undergo apoptosis. Receptor-independent stimulation of Tgfb1(-/-) T cells by PMA plus ionomycin induces IL-2 production and mitogenic response, and it rescues them from anergy. Tgfb1(-/-) T cells display decreased CD3 expression; increased expression of the activation markers LFA-1, CD69, and CD122; and increased cell size, all of which indicate prior activation. Consistently, mutant CD4(+) T cells have elevated intracellular Ca(2+) levels. However, upon subsequent stimulation in vitro, increases in Ca(2+) levels are less than those in wild-type cells. This is also consistent with the anergic phenotype. Together, these results demonstrate that the ex vivo proliferative hyporesponsiveness of Tgfb1(-/-) splenic lymphocytes is due to prior in vivo activation of T cells resulting from deregulated intracellular Ca(2+) levels.

Predictive medicine: severe trauma and burns

Severe trauma and burn injury are often associated with a life-threatening systemic inflammatory response, only to be followed by severe infections. Although many parameters of the immune system are depressed or altered, only the innate immune system has been directly correlated with infections in these patients. The innate immune system plays an important role in both the inflammatory response and defense against infections. These types of sequelae suggest that at any particular point in time, depending upon the patient status, either a hyperactive or suppressed polymorphonuclear neutrophil (PMN) response may be detected. In fact, this dichotomy has been shown to occur in numerous published studies.

TGF beta 1 inhibits Ca2+-calcineurin-mediated activation in thymocytes

TGFbeta1 is a polypeptide growth modulatory and differentiation factor involved in many biological processes including immune homeostasis and self-tolerance. Tgfb1 knockout mice die around weaning age due to severe inflammation in most major organ systems, but the mechanism underlying this disease is not understood. In this study we demonstrate that Tgfb1(-/-) CD4(+)CD8(+) and CD4(+)CD8(-) thymocytes are hyperresponsive to receptor-mediated and receptor-independent mitogenic stimulation. A suboptimal concentration of ionomycin in the presence of PMA fully activates Tgfb1(-/-) thymocytes, whereas the inhibitors of Ca(2+) influx and calcineurin, EGTA and FK506, eliminate the hyperresponsiveness. Hence, the hypersensitivity of Tgfb1(-/-) thymocytes is due to a lowered threshold for Ca(2+)-dependent activation. Further, we demonstrate that the hypersensitivity of thymocytes results from the absence of TGFbeta1 and not from the inflammatory environment because the thymocytes are hyperresponsive in preinflammatory-stage Tgfb1(-/-) mice. Our results suggest for the first time that TGFbeta1 functions to inhibit aberrant T cell expansion by maintaining intracellular calcium concentration levels low enough to prevent a mitogenic response by Ca(2+)-independent stimulatory pathways alone. Consequently, TGFbeta1 prevents autoimmune disease through a Ca(2+) regulatory pathway that maintains the activation threshold above that inducible by self-MHC-TCR interactions.

The APC tumor suppressor controls entry into S-phase through its ability to regulate the cyclin D/RB pathway

BACKGROUND & AIMS

APC gene mutation is an early alteration in most colorectal tumors. In an attempt to determine its role in tumor development, we asked whether reintroducing wild-type APC into colorectal cancer cells with mutant APC affected cell cycle progression.

METHODS

Using transient transfection, a plasmid containing the APC complementary DNA and DNA encoding the green fluorescent protein was expressed in SW480 cells. In addition, several other constructs were co-expressed with APC to determine their combined effects.

RESULTS

We report that colorectal cancer cell lines transfected with wild-type APC arrest in the G(1)- phase of the cell cycle and that this arrest is abrogated by cotransfecting constitutively active beta-catenin or cyclin D1 and cMYC together. This APC-induced cell cycle arrest involves the disruption of beta-catenin-mediated transcription and depends on components of the G(1)/S regulatory machinery, as overexpression of E1a or E2F-1, -2, or -3 overrides the G(1) arrest. Consistent with this, APC transfection inhibits RB phosphorylation and reduces levels of cyclin D1.

CONCLUSIONS

Our results suggest that APC functions upstream of RB in the G(1)/S regulatory pathway, cyclin D1 and cMYC affect APC-mediated arrest equivalently to oncogenic beta-catenin, and most colon tumors disrupt control of G(1)/S progression by APC mutation.

Differential effects of two different routes of immunization on protection against gram-negative sepsis by a detoxified Escherichia coli J5 lipopolysaccharide group B meningococcal outer membrane protein complex vaccine in a burned mouse model

Gram-negative sepsis causes morbidity and mortality in burned patients. To determine whether immunization with core endotoxin (lipopolysaccharide) via one of two routes could protect burned mice from septic death, mice were immunized either three times subcutaneously (SC) or one time intramuscularly (IM) then two times intraperitoneally (IP) with a core-lipopolysaccharide vaccine. Control mice were immunized with either saline or an irrelevant antigen. Postimmunization, mice were immunocompromised with a 15% TBSA flame burn and challenged subeschar with Klebsiella pneumoniae or Escherichia coli. Vaccine immunization improved the survival of both E. coli- and K. pneumoniae-challenged mice when given SC but not when given IM, IP. Postimmunization, total immunoglobulin titers were elevated over preimmune titers, but titers in IM, IP-immunized mice were higher than those in SC-immunized mice. Both isotyping and flow cytometry studies indicated that sera from mice immunized via IM, IP opsonized better than sera from mice immunized via SC. Hence, this vaccine provided route-specific protection of burned mice against gram-negative sepsis; its mechanism of action was not solely dependent upon increased immunoglobulin titers or phagocytosis.

Oral arginine improves blood pressure in renal transplant and hemodialysis patients

BACKGROUND

Hypertension in kidney transplant (KT) patients may result from attenuated whole-body nitric oxide (NO) content and abnormal NO-mediated vasodilation. Increasing NO bioavailability with L-arginine (ARG) could theoretically restore the NO-mediated vasodilatory response and lower blood pressure.

METHODS

In a prospective pilot study, 6 normotensive volunteers and 10 KT patients received oral supplements of ARG (9.0 g/d) for 9 days, then 18.0 g/d for 9 more days. Six hemodialysis (HD) and 4 peritoneal dialysis patients received the same dose for 14 days. Five KT patients received 30 mL/d of canola oil (CanO) in addition to ARG. Systolic (SBP) and diastolic (DBP) blood pressure, creatinine clearance (CCr), and serum creatinine (Cr) were measured at baseline, day 9, and day 18. In a subsequent study, 20 hypertensive KT patients with stable but abnormal renal function were randomized in a crossover study to start ARG-only or ARG+CanO supplements for two 2-month periods with an intervening month of no supplementation. SBP, DBP, CCr, and Cr were measured monthly for 7 months.

RESULTS

In the pilot study, ARG reduced the SBP in HD patients from 171.5 +/- 7.5 mmHg (baseline) to 142.8 +/- 8.3 mmHg (p = .028). In the crossover study, SBP was reduced from baseline (155.9 +/- 5.0 mmHg), after the first 2 months (143.2 +/- 3.2 mmHg; p = .03) and subsequent 2 months (143.3 +/- 2.5 mmHg; p = .014) of supplementation. DBP was also reduced after supplementation in both studies. CanO had no effect on blood pressure. Renal function did not change.

CONCLUSIONS

Oral preparations of ARG (+/-CanO) were well tolerated for up to 60 consecutive days and had favorable effects on SBP and DBP in hypertensive KT and HD patients.

Inhibition of melanosome transfer from melanocytes to keratinocytes by lectins and neoglycoproteins in an in vitro model system

We propose that some of the critical molecules involved in the transfer of melanosomes from melanocytes to keratinocytes include plasma membrane lectins and their glycoconjugates. To investigate this mechanism, co-cultures of human melanocytes and keratinocytes derived from neonatal foreskins were established. The process of melanosome transfer was assessed by two experimental procedures. The first involved labeling melanocyte cultures with the fluorochrome CFDA. Labeled melanocytes were subsequently co-cultured with keratinocytes, and the transfer of fluorochrome assessed visually by confocal microscopy and quantitatively by flow cytometry. The second investigative approach involved co-culturing melanocytes with keratinocytes, and processing the co-cultures after 3 days for electron microscopy to quantitate the numbers of melanosomes in keratinocytes. Results from these experimental approaches indicate significant transfer of dye or melanosomes from melanocytes to keratinocytes that increased with time of co-culturing. Using these model systems, we subsequently tested a battery of lectins and neoglycoproteins for their effect in melanosome transfer. Addition of these selected molecules to co-cultures inhibited transfer of fluorochrome by approximately 15-44% as assessed by flow cytometry, and of melanosomes by 67-93% as assessed by electron microscopy. Therefore, our results suggest the roles of selected lectins and glycoproteins in melanosome transfer to keratinocytes in the skin.

Nutritional immunomodulation leads to enhanced allograft survival in combination with cyclosporine A and rapamycin, but not FK506

BACKGROUND

Recently, specific immunonutrients were found to increase experimental allograft survival when combined with cyclosporine A (CsA). This study compared the effect on rat cardiac allograft survival when nutritional immunomodulation was used with CsA, rapamycin (Rapa), or tacrolimus (FK506).

METHODS

Intra-abdominal ACI to Lewis cardiac allografts were performed and assessed daily by palpation. Study groups included untreated controls and those receiving CsA, Rapa, or FK506. Rats were fed ad libitum with Impact diet (fortified with fish oil, arginine, and RNA) or standard rat food. Further study groups were transplanted that received a donor-specific transfusion in addition to immunosuppression and diet.

RESULTS

Allograft survival was extended by combining Impact with CsA (45.3+/-19 days) and Rapa (165.3+/-52 days), but not FK506 (12.4+/-3.2 days). Mean graft survival in the Rapa/Impact group met criteria for functional tolerance. The addition of a donor-specific transfusion did not lead to graft survival advantages over similar groups not receiving a donor-specific transfusion.

CONCLUSIONS

The use of immunonutrients improves transplant outcome in animals treated with short courses of CsA and Rapa, but not FK506. These findings highlight the potential differences in the effects of nutritional immunomodulation with different immunosuppressive drugs in the treatment of transplant patients.

Altered gene expression in melanocytes exposed to 4-tertiary butyl phenol (4-TBP): upregulation of the A2b adenosine receptor 1

Exposure to phenolic agents contributes to the development of occupational vitiligo. Proposed as a causative factor for leukoderma in vivo, the para-substituted phenol 4-tertiary butyl phenol was chosen to investigate early cellular events responsible for selective disappearance of melanocytes from the epidermis of individuals sensitive to such agents. To this end, differential display of melanocyte mRNA isolated from three separate cultures was performed following a 12 h exposure of cells to 250 microM 4-tertiary butyl phenol or to vehicle alone. Fragments of cDNA representing differentially expressed messages were cloned and subsequently confirmed by reverse dot blotting. Alignment analysis revealed that the L30 ribosomal protein was upregulated by the treatment, potentially reflecting altered levels of protein synthesis in response to stress. In addition, a gene sequence upregulated following exposure to 4-tertiary butyl phenol was identified as the A2b receptor (a P1 receptor for adenosine). Differential expression of this gene was confirmed in an RNase protection assay. By reverse transcription-polymerase chain reaction, the gene was shown to be expressed in keratinocytes and fibroblasts as well. Flow cytometry confirmed differential expression in melanocytes and fibroblasts, but not in keratinocytes. Interestingly, it has been reported that P1 purinoceptor stimulation can induce apoptosis. This is in concordance with results reported elsewhere demonstrating induction of apoptosis by 4-tertiary butyl phenol in human melanocytes, as well as with morphologic changes observed in this study in cells exposed to 250 microM 4-tertiary butyl phenol for 72 h. In conclusion, differential display is useful to establish melanocyte components involved in the cellular response to phenolic agents.

Heat shock response: presence and effects in burn patient neutrophils

Heat shock proteins (HSPs) are present in neutrophils (PMNs) from critically ill patients. We investigated whether HSPs were present in PMNs from burn patients and whether heat shock contributed to the functional defects observed in burn PMNs. Using both flow cytometry and Western blot techniques it was observed that inducible HSP72 (iHSP72) was present in PMNs and leukocytes from burn patients, especially in patients with inhalation injury. Similar to burn PMNs, and in contrast to normal cells, heat shocked PMNs (43 degrees C incubation) expressed iHSP72 and were unable to increase the expression of CD11b/CD18 in response to pro-inflammatory stimuli. Degranulation after pro-inflammatory stimuli was decreased for both burn- and heat-shocked PMNs when compared to normal controls. In burn PMNs these functional abnormalities were mainly due to decreased quantities of proteins (CD11b, albumin, B12 binding protein, beta-glucuronidase) present within cytoplasmic granules. However, in heat-shocked PMNs the abnormalities were primarily related to abnormal exocytosis. In conclusion, our data show that decreased quantities of cytoplasmic granule proteins and, to a smaller degree, defective exocytosis are involved in the functional abnormalities observed in burn PMNs.

Quantitation of phagocytosis by confocal microscopy

Confocal microscopy is an excellent tool to quantify phagocytosis. Depending on the particle used, phagocytosis can be determined by the simple manual counting of internalized particles. If a fluorescence probe is utilized, an analysis of fluorescence intensity can be used for quantification. The basic procedure can be altered in a number of areas to conform with the scientific needs of the investigator. This includes the use of different particles, cell types, fluorescence dyes, and even the degree of sophistication of the instrumentation. The major pitfall encountered when trying to quantify phagocytosis is the inability to separate external from internal (phagocytosed) particles. If not determined properly, data will be erroneous, usually indicating a much higher degree of phagocytosis than actually occurred.

Tumor necrosis factor alpha regulates CXC chemokine receptor expression and function

The alpha chemokine family is central to the participation of neutrophils in the acute inflammatory response. These substances interact with neutrophils through two cell surface receptors, CXCR-1 and CXCR-2 (formally known as IL-8R-1 and IL-8R-2). We investigated the possible regulatory effects of tumor necrosis factor alpha (TNFalpha) pretreatment on CXCR-1 and CXCR-2. To this end, we examined these receptors with flow cytometry, radioligand binding, Northern blot analyzes, calcium mobilization, and chemotaxis experiments on human neutrophils. In flow cytometry experiments, TNFalpha pretreatment substantially decreased cell surface CXCR-2 receptor levels but showed partial recovery at 120 min. On the other hand, CXCR-1 receptor levels had a sharp decline at 15 min and maintained that level to 120 min. Northern blot analyzes showed that mRNA levels of both IL-8 receptors were essentially unchanged after 45 min of TNFalpha pretreatment, but declined markedly following 2 h of pretreatment. Chemotaxis experiments on cells treated with TNFalpha for 5-120 min showed a substantial down-regulation of chemotaxis to IL-8 and GROalpha. This was noted to be much greater than the decline in cell surface receptors. Calcium mobilization experiments revealed minimal inhibition of the IL-8-induced increase in calcium after pretreatment with TNFalpha, but the response to NAP-2 was substantially inhibited. The data demonstrate differential regulation of the IL-8 receptor.

The effect of nutritional immunomodulation on cardiac allograft survival in rats receiving mycophenolate mofetil, cyclosporine A, and donor-specific transfusion

BACKGROUND

Immunosuppressive drugs continue to pose significant risks such as infection, toxicity, or neoplasia when used in long-term therapy. The investigation of newer and safer combined treatment strategies that decrease the need for these drugs is becoming increasingly important. Immunonutrients are known to have significant modulating effects on the immune system. Feeding with Impact, a commercially available diet enriched with arginine, omega-3 fatty acids, and RNA, recently has been shown to extend rat cardiac allograft survival when combined with a donor-specific transfusion (DST) and cyclosporine A (CsA). Because mycophenolate mofetil (MMF) is now commonly used in the clinical setting, the current study was designed to examine the effect on rat cardiac allograft survival when MMF was added to this immunosuppressive regimen.

METHODS

Intra-abdominal ACI to Lewis heterotopic cardiac allografts were performed. Study groups included untreated controls and recipients receiving varying combinations of a DST (1 mL) on the day prior to engraftment, MMF 45 mg/kg/day from the day of transplant through postoperative day six, and CsA 10 mg/kg on the day prior to operation and 2.5 mg/kg from the day of transplant through postoperative day 6. Animals were fed ad libitum with Impact diet or standard lab chow. Graft survival was determined by cessation of a palpable heartbeat.

RESULTS

Treatment with MMF led to a prolonged allograft survival over historical untreated controls. The combination of MMF with a donor-specific transfusion, Impact, or CsA was associated with an increase in graft survival over MMF alone. The addition of Impact to the combination of MMF and CsA resulted in further improvement. The most pronounced graft survival advantage was seen when Impact was combined with a DST and both of the immunosuppressive agents. One quarter of the animals in this group had a palpable donor heart beat at greater than 150 days, indicating functional tolerance in those animals.

CONCLUSIONS

The administration of Impact diet to treatment groups in this study was associated with graft survival advantages when compared to most of the other study groups receiving a similar drug regimen and standard chow. These findings support the importance of nutritional influences on allograft survival, and highlight the potential of diet therapy when used with short courses of clinically relevant immunosuppressive drugs.

Temporal inhibition of calmodulin in the nucleus

Calmodulin (CaM) acts as a primary mediator of calcium signaling by interacting with target proteins. We have previously shown that nuclear CaM is critical for cell cycle progression using a transgene containing four repeats of a CaM inhibitor peptide and nuclear targeting signals (J. Wang et al., J. Biol. Chem. 270 (1995) 30245 30248; Biochim. Biophys. Acta 1313 (1996) 223-228). To evaluate the role of CaM in the nucleus specifically during S phase of the cell cycle, a motif which stabilizes the mRNA only during S phase was included in the transgene. The CaM inhibitor mRNA transcript contains a self-annealing stem-loop derived from histone H2B at the 3' end. This structure provides stability of the mRNA only during S phase, thereby restricting CaM inhibitor expression to S phase. The inhibitor accumulates in the nucleus, particularly in the nucleoli. Flow cytometric analysis demonstrated that the CaM inhibitor is expressed in S and G2. Transfected cells show growth inhibition and a reduction in DNA synthesis. The CaM inhibitor peptide is a versatile reagent that allows spatial as well as temporal dissection of calmodulin function.

Dietary omega-3 and omega-9 fatty acids uniquely enhance allograft survival in cyclosporine-treated and donor-specific transfusion-treated rats

BACKGROUND

Both laboratory and clinical studies have shown that dietary lipids may affect immunologic responses. This study was conducted to compare different classes of long-chain unsaturated fatty acids for their effect on allograft survival in animals receiving a donor-specific transfusion and a short course of low-dose cyclosporine (CsA).

METHODS

Heterotopic ACI strain cardiac allografts were transplanted to Lewis strain rat recipients given diets with different lipid composition. In experiment 1, animals received CsA for 14 days and different diets were enriched with lipids with high concentrations of omega-3, omega-6, or omega-9 fatty acids. In experiment 2, animals received CsA for only 8 days and different diets were enriched with corn oil (omega-6), canola oil (omega-3 and omega-9), fish oil (omega-3) or a mixture of sunflower oil and fish oil (omega-3 and omega-9).

RESULTS

In experiment 1, animals receiving the diet with 30% sunflower oil had the best allograft survival (200+/-42 days vs. 53+/-8 days for regular chow plus donor-specific transfusion and CsA, P<0.05). In experiment 2, diets containing canola oil (a mixture of omega-3 and omega-9 fatty acids) were associated with the best survival (P=0.0011 vs. regular chow).

CONCLUSION

Dietary omega-3 and omega-9 fatty acids both enhanced cardiac allograft survival in a stringent rat strain combination. Canola oil is a convenient oil for administering both alpha-linoleic acid (omega-3) and oleic acid (omega-9) in a palatable form for human consumption. Further investigation of the potential usefulness of lipids in transplant therapy is warranted.

Azurophilic granules of human neutrophils contain CD14

CD14, the leukocyte receptor for lipopolysaccharide (LPS), is important in the response of human polymorphonuclear leukocytes (PMNs) to infection with gram-negative bacteria. The level of CD14 on the PMN surface increases after exposure to some inflammatory stimuli such as N-formyl-methionyl-leucyl-phenylalanine (fMLP). These newly expressed CD14 molecules probably come from an intracellular pool of preformed receptors. We sought to further characterize PMN CD14 expression, upregulation, and shedding and to define the intracellular location of CD14 molecules. Our results demonstrate that both LPS and fMLP significantly increased CD14 cell surface expression; however, neither phorbol myristate acetate (PMA) or A23187 increased receptor levels on the PMN surface. Neither fMLP, PMA, or A23187 stimulated the release of soluble CD14 from PMNs. Intracellular CD14 was observed in >90% of PMNs examined by flow cytometry and confocal microscopy. Additional analyses using CD14 enzyme-linked immunosorbent assays and electron microscopy studies, examining PMN granules separated by discontinuous sucrose or Percoll gradients, showed that CD14 was present in both the plasma membrane-secretory vesicle fractions and azurophilic granules.

Regulation of pigmentation in cultured skin substitutes by cytometric sorting of melanocytes and keratinocytes

Unpredictable pigmentation in cultured skin substitutes (CSS) is an anatomic deficiency after wound treatment and can require years to normalize. Variable numbers of human melanocytes (HM) survive in cultures of human keratinocytes (HK) as demonstrated by focal areas of pigmentation in CSS after healing. The purposes of this study were to deplete HM from HK cultures and to regulate the numbers of HM contained in CSS. A highly pigmented HM cell strain was chosen for these studies to emphasize the differences in light scattering between HK and HM by flow cytometry. Cytometric gates were set with selective cultures of HM and HK and were used to sort a mixed population of HK + 4% HM. After sorting, CSS were prepared from human fibroblasts attached to collagen-glycosaminoglycan sponges combined with cells from the HK + 4% HM (pre-treatment control), the sorted HK (experimental), or sorted HK + 3% HM (post-treatment positive control) subpopulations and grafted to athymic mice. Grafted wounds were assessed for 6 wk by planimetry for area of pigment and by a Minolta Chromameter for color density and hue in situ. Histology and staining of HLA-ABC were performed at 6 wk. Data from percent pigmented area and chromameter measurements identified quantitative and statistically significant decreases in color of healed skin after flow cytometric separation of HK and HM. Therefore, a purified HK subpopulation depleted of HM was isolated by flow cytometry that generated healed skin with reduced pigmentation. These results suggest that HM can be selectively depleted from HK cultures and then added to cultured skin substitutes at specific densities to generate predictable pigmentation for improved function and cosmesis in healed wounds.

A strategy for generating consistent long-term donor-specific tolerance to solid organ allografts

Current triple drug immunosuppression while effective, increases the risk of opportunistic infection and lymphoproliferative disorders. An alternative strategy would be the generation of donor-specific tolerance with short-term treatment. The use of donor-specific transfusions (DST) with a single brief course of cyclosporine (CsA) and rapamycin (Rapa) has produced promising results in animal models, but falls short of uniform tolerance. It was hypothesized that a DST/CsA/Rapa protocol administered in the perioperative period and redosed at one month might improve on this success in the ACI to Lewis rat heterotopic cardiac transplant model. Recipients received no treatment (group 1), a 1 ml DST intravenously (i.v.) with CsA 10 mg/kg subcutaneously (s.c.) at D-1 and CsA 2.5 mg/kg DO6D+13 (group 2), DST/CsA as dosed above with intraperitoneally (i.p.) Rapa 1 mg/kg D+36D+7 (group 3), DST/CsA/Rapa as above with all components redosed at one month (group 4), DST/CsA/Rapa with only CsA and Rapa repeated (group 5), and DST/CsA/Rapa with CsA redosed and Rapa continued indefinitely (group 6). Comparison of permanent survival (longer than 200 days) between protocols revealed groups 4-6 were significantly greater than control groups 1-3. Donor specificity was verified in group 6, where three permanent survivors received a second cardiac allograft from a Buffalo rat donor and rejected these grafts almost as quickly as untreated strain pair matched controls 21 +/- 1 days vs 30.3 +/- 5 days. Animals from group 6 displayed a greatly reduced mixed lymphocyte response to ACI cells but not to third-party cells. The percentage of T cells producing cytokines was reduced and shifted toward Th-2 type cytokines (IL-4). Thus, a repeated cycle of this brief DST/CsA/Rapa treatment appears to generate consistent permanent graft survival (up to 91%) that exceeds previously studied tolerance inducation protocols and is donor specific.

Neutrophils from burn patients are unable to increase the expression of CD11b/CD18 in response to inflammatory stimuli

Neutrophils (PMNs) from patients with thermal injury are dysfunctional for the CD11b/CD18-dependent functions of diapedesis, chemotaxis, and phagocytosis. The expression of CD11b/CD18 on normal PMNs is increased after an inflammatory stimulus. We proposed that CD11b/CD18 expression on burn patient PMNs would respond abnormally to inflammatory stimuli. PMNs were obtained from nonseptic burn patients during the second week after thermal injury. PMNs from burn patients incubated with lipopolysaccharide (LPS), N-formyl-methionyl-leucyl-phenylalanine, phorbol myristate acetate, or A23187 did not increase the expression of CD11b/CD18 to the same degree exhibited by normal PMNs. This inability to increase CD11b/CD18 was not due to differences in CD14 receptor expression, LPS binding, or factors present in the serum of burn patients. The upregulation of CD35 also was decreased on burn patient PMNs. Western blot analysis revealed decreased quantities of CD11b protein in burn patient PMNs compared with normal control PMNs. The deficiency in CD11b/CD18 expression after inflammatory stimuli may explain some of the abnormalities observed in burn PMN function.

A novel flow cytometric method for quantifying phagocytosis of apoptotic cells

Many eukaryotic cell types are capable of specific recognition and phagocytosis of apoptotic cells, and there is increasing interest in the mechanisms involved in this process. To facilitate analysis of these mechanisms, we designed a novel fluorescence-based method to quantify phagocytosis in vitro using endothelial cell engulfment of apoptotic cells as a model. The B-cell line WEHI-231 was labeled with the fluorophore 5-(&-6)-carboxytetramethyl-rhodamine-succinimidyl-ester (TAMRA) and then induced to undergo apoptosis by crosslinking cell surface immunoglobulin. An endothelial cell line was subsequently allowed to ingest these TAMRA-labeled apoptotic lymphocytes. After 24 h, nonbound lymphocytes were removed and the mono-layers were dissociated. Any nonphagocytosed lymphocytes that remained tightly bound to the endothelial cells were then indirectly immunofluorescein labeled for the pan leukocyte-specific marker CD45. Flow cytometric analysis of the cells distinguished three endothellal cell populations: 1) endothelial cells with surface bound lymphocytes (TAMRA+ CD45+); 2) endothelial cells containing phagocytosed apoptotic lymphocytes (TAMRA+ CD45-); and 3) endothelial cells that were not associated with lymphocytes. The identification of these populations was verified by confocal microscopy of sorted cells. The method described herein will facilitate detailed studies on phagocytic recognition of apoptotic cells and should have broad applications to other phagocytic cell systems.