A highly immunogenic trivalent T cell receptor peptide vaccine for multiple sclerosis

Background: T cell receptor (TCR) peptide vaccination is a novel approach to treating multiple sclerosis (MS). The low immunogenicity of previous vaccines has hindered the development of TCR peptide vaccination for MS. Objective: To compare the immunogenicity of intramuscular injections of TCR BV5S2, BV6S5 and BV13S1 CDR2 peptides in incomplete Freund’s adjuvant (IFA) with intradermal injections of the same peptides without IFA. Methods: MS subjects were randomized to receive TCR peptides/IFA, TCR peptides/saline or IFA alone. Subjects were on study for 24 weeks. Results: The TCR peptides/IFA vaccine induced vigorous T cell responses in 100% of subjects completing the 24-week study (9/9) compared with only 20% (2/10) of those receiving the TCR peptides/saline vaccine (P =0.001). IFA alone induced a weak response in only one of five subjects. Aside from injection site reactions, there were no significant adverse events attributable to the treatment. Conclusions: The trivalent TCR peptide in IFA vaccine represents a significant improvement in immunogenicity over previous TCR peptide vaccines and warrants investigation of its ability to treat MS.

Phenotypic analysis of human immunodeficiency virus (HIV) type 1 cell-mediated immune responses after treatment with an HIV-1 immunogen

It was hypothesized that immune recognition could be stimulated with combined immune-based and potent antiviral drug therapies. This study examined human immunodeficiency virus type 1 (HIV-1)-specific lymphocyte proliferation before and after treatment with an inactivated HIV-1 immunogen in 15 chronically infected HIV-1 seropositive subjects. Lymphocyte proliferation to the immunizing antigen (gp120-depleted HIV-1; P<.001), purified native p24 (P<.001), and recombinant p24 (P<.05) increased after treatment with the HIV-specific immune-based therapy. By HIV-1 antigen-specific flow cytometry, T helper CD4 lymphocytes, CD8 lymphocytes, and NK cells (all P<.001) were the predominant cell types proliferating in vitro after treatment. Additional phenotyping of proliferating cells revealed predominantly CD4 and CD8 memory (both P<.001) phenotypes. This study supports the concept that in vitro lymphocyte proliferation to HIV-1 antigens, augmented after treatment with an inactivated HIV-1 immunogen, involves primarily CD4 and CD8 cell memory immune responses.

Preliminary evaluation of human immunodeficiency virus type 1 (HIV-1) immunogen in children with HIV-1 infection

The safety and preliminary activity of human immunodeficiency virus type 1 (HIV-1) immunogen were evaluated in 10 HIV-1-infected children with disease stage N1,2 or A1,2. Multiple inoculations of 2. 5 or 10 units (U) of HIV-1 immunogen were safe and well tolerated without an acceleration of disease progression. When antiretroviral agents were coadministered, the 10 U dose appeared to be associated with more sustained reduction in plasma HIV-1 RNA than the 2.5 U dose (median log10 HIV-1 RNA at month 18, 3.07 vs. 4.01 copies/mL in 10 U [n=4] vs. 2.5 U [n=3], respectively; P=.034). Levels of regulated-on-activation, normal T cell-expressed and -secreted chemokine produced from HIV-1 immunogen-stimulated lymphocytes in vitro were increased in the children who had HIV-1 immunogen-specific antibody responses (P<.02) and appeared to be inversely correlated with levels of plasma HIV-1 RNA (P<.01). These preliminary data warrant larger studies to determine the effectiveness of adjunctive therapy with HIV-1 immunogen in children with HIV-1 infection.

Effect of HIV-specific immune-based therapy in subjects infected with HIV-1 subtype E in Thailand

OBJECTIVE

To examine the effect of treatment with an inactivated, gp120-depleted, HIV-1 immunogen (Remune) in 30 Thai subjects infected with HIV-1 subtype E.

DESIGN

Sixty-week open-label study.

METHODS

Thirty HIV-positive volunteers with CD4 cell counts > or = 300 x 10(6)/l were given intramuscular injections of Remune into the triceps muscle on day 1 and then at weeks 4, 8, 12, 24, 36, 48 and 60.

RESULTS

Treatment with Remune was well-tolerated and augmented HIV-1-specific immune responses. Furthermore, subjects had a significant increase in CD4 cell count (P < 0.0001), CD4 cell percentage (P < 0.0001), CD8 cell percentage (P < 0.0001), and body weight (P < 0.0001) compared with pretreatment levels. Fourteen subjects with detectable viral load at day 1 showed a decrease at week 60 (P=0.04). Retrospective Western blot analysis showed 23 subjects with increased intensity of antibody bands and 15 patients showed development of new reactivities to HIV proteins, especially towards p17 and p15.

CONCLUSION

These results indicate that HIV-specific immune-based therapeutic approaches such as Remune should be further examined in countries with different clades of HIV-1 and where access to antiviral drug therapies is limited.

A primer on HIV type 1-specific immune function and REMUNE

The ability to recognize HIV antigens is lost early in HIV-1 infection. Individuals with nonprogressive HIV disease have been observed to mount strong immune responses against the virus and have become a paradigm to emulate with immune-based therapies. Highly active antiviral drug therapy (HAART) has now become the standard of care for HIV-1-infected individuals. Because HIV-specific anergy occurs early in HIV infection, HAART initiated after primary infection may not reconstitute HIV-specific immune function. We have been investigating the effects of an immune-based therapy, called REMUNE, in HIV-1-seropositive individuals. REMUNE has been observed to stimulate HIV-1-specific immune function measured by delayed-type hypersensitivity, lymphocyte proliferation, Th1 cytokine, and beta-chemokine production. Multiple Phase II studies and a Phase III clinical end-point study are ongoing in thousands of seropositive individuals in order to test the clinical utility of REMUNE. The clinical testing of REMUNE and other promising immune-based therapies may provide additional treatment modalities useful in the chronic management of HIV-1.

In vitro p24 antigen-stimulated lymphocyte proliferation and beta-chemokine production in human immunodeficiency virus type 1 (HIV-1)-seropositive subjects after immunization with an inactivated gp120-depleted HIV-1 immunogen (Remune)

We examined the effect of immune stimulation by a human immunodeficiency virus type 1 (HIV-1) immunogen (Remune) compared to a non-HIV vaccine (influenza) on HIV-1-specific immune responses in HIV-1-seropositive subjects. HIV-1 p24 antigen-stimulated lymphocyte proliferation was not augmented after immunization with the influenza vaccine. In contrast, subjects increased their lymphocyte proliferative responses to p24 antigen after one immunization with HIV-1 immunogen (Remune) (gp120-depleted inactivated HIV-1 in incomplete Freund's adjuvant). Furthermore, p24 antigen-stimulated beta-chemokine production (RANTES, MIP-1alpha, MIP-1beta) was also augmented after immunization with the HIV-1 immunogen but not influenza vaccine. Taken together, these results suggest that in this cohort, HIV-specific immune responses to p24 antigen can be augmented after immunization with an HIV-1 immunogen. The ability to upregulate immune responses to the more conserved core proteins may have important implications in the development of immunotherapeutic interventions for HIV-1 infection.

Cross-clade immune responses after immunization with a whole-killed gp120-depleted human immunodeficiency virus type-1 immunogen in incomplete Freund's adjuvant (HIV-1 immunogen, REMUNE) in human immunodeficiency virus type-1 seropositive subjects

Lymphocyte proliferation responses to gp120-depleted HZ321 virus (clade A) antigen were compared to BAL human immunodeficiency virus (HIV) virus antigen (clade B) responses, clade E HIV virus antigen responses, and purified native p24 antigen responses in 15 human immunodeficiency virus type-1 (HIV-1) seropositive subjects immunized with a whole-killed inactivated gp120-depleted HIV-1 antigen in Incomplete Freund's adjuvant (HIV-1 immunogen, REMUNE). A significant increase in lymphocyte proliferation to HZ321 antigen was observed after immunization with the HIV-1 immunogen (p = 0.02). A strong association was demonstrated between the HIV-1 immunizing antigen, HZ321, and native p24 antigen responses (r = 0.80, p < 0.0001). Furthermore, a strong association in terms of proliferative responses was demonstrated between HZ321 virus (clade A) responses and BAL virus (clade B) (r = 0.95, p < 0.0001) and clade E virus antigen (r = 0.92, p < 0.0001). Proliferative responses to HIV antigens also correlated with baseline CD4 counts. Taken together, these results support the specificity of immune responses induced by REMUNE (HIV-1 immunogen). The development of cross-reactive immune responses between clades and to the more conserved epitopes of the virus have implications in the development of therapeutic and prophylactic HIV vaccines.

Safety and immunogenicity of REMUNE in HIV-infected Thai subjects

The safety and immunogenicity of REMUNE, an HIV-specific immune based therapy for HIV infection, was evaluated in a cohort of 30 HIV infected subjects in Thailand. This therapy utilizes a gp120 depleted inactivated virus (HZ321), which exhibits a high degree of conservation with the core antigens of both type B' and E strains of HIV, the predominant Thailand isolates. The treatment was well tolerated, with no serious adverse events reported over the course of the 4-month trial. Treatment in which four doses were administered with REMUNE appeared to boost HIV-specific immune responses, with approximately 75% of the treated subjects demonstrating an increase in either the repertoire or the intensity of the serological response to HIV as measured by Western blot. CD4%, viral load, and weight remained stable over the course of the 4-month study relative to baseline values. Viral subtyping of this cohort revealed a predominance of type 'E'. These data suggest that REMUNE is safe and immunogenic in seropositive Thai subjects and supports further study of the therapeutic potential of REMUNE to treat HIV-1 infection.

Tumor necrosis factor alpha and human immunodeficiency virus-specific functional immune responses after immunization with Gp120-depleted, inactivated HIV-1 in incomplete Freund's adjuvant (REMUNE) in HIV-1-seropositive subjects

OBJECTIVE

We examined the relation between tumor necrosis factor-alpha (TNF-alpha) levels and human immunodeficiency virus type 1 (HIV-1)-specific functional immune responses, as measured by HIV-1 antigen-stimulated lymphocyte proliferation and beta-chemokine production after immunization with gp120-depleted, inactivated HIV-1 in incomplete Freund's adjuvant (i.e., HIV-1 Immunogen; REMUNE, The Immune Response Corporation, Carlsbad, CA, U.S.A.).

STUDY DESIGN/METHODS

HIV-1-seropositive subjects who enrolled in an open-label study were immunized with REMUNE every 12 weeks and monitored for 60 weeks. HIV-1 antigen-stimulated lymphocyte proliferation and RANTES production were measured in peripheral blood mononuclear cells (PBMCs). TNF-alpha levels were measured in serum.

RESULTS

TNF-alpha (P = 0.0003) significantly decreased and HIV-1 antigen-stimulated RANTES production (P = 0.002) and lymphocyte proliferation (P = 0.07) increased after immunization with REMUNE. TNF-alpha levels negatively correlated with HIV-1 antigen-stimulated RANTES production (r = -0.71; P = 0.0002) and lymphocyte proliferation (r = -0.37; P = 0.09).

CONCLUSIONS

This study demonstrated decreased TNF-alpha levels with a concomitant augmentation of HIV-specific functional immunity in subjects immunized with REMUNE. Because TNF-alpha has been implicated in the induction of anergy in HIV-1 infection, the ability to decrease TNF-alpha may allow the immune system to respond to HIV and non-HIV antigens. Larger studies are being conducted to confirm the clinical utility of REMUNE in combination with potent antiviral drugs.

HIV-1-Specific Functional Immune Measurements as Markers of Disease Progression

The impairment of lymphocytes to proliferate to HIV antigen is a relatively early functional defect of cell-mediated immunity found in HIV-infected individuals. The finding of strong proliferative responses in nonprogressive HIV disease as well as its inverse association with viral load and clinical manifestation of AIDS supports the further use of this marker as a surrogate of disease progression. The observation that HIV-specific lymphocyte proliferation is associated with the production of CD8-derived HIV suppressive factors such as the beta-chemokines further supports this conclusion. These functional immune measurements provide an additional marker to monitor disease progression in HIV-infected individuals, along with the current standards of CD4 counts and viral load. Copyright 1997 S. Karger AG, Basel

Effect of immunization with an inactivated gp120-depleted HIV-1 immunogen on beta-chemokine and cytokine production in subjects with HIV-1 infection

OBJECTIVE

To measure beta-chemokine and cytokine production in HIV-1-infected subjects undergoing treatment with HIV-1 immunogen (REMUNE).

DESIGN

Open label treatment study.

METHODS

beta-Chemokine and cytokine production in peripheral blood mononuclear cell (PBMC) culture.

RESULTS

Interferon-gamma production (p = 0.04) and lymphocyte proliferation (p = 0.001) to HIV-1 antigen-stimulated PBMCs increased after immunization with the HIV-1 immunogen. A correlation was demonstrated after immunization between HIV-1 antigen-stimulated lymphocyte proliferation and interferon-gamma levels (r = 0.53, p = 0.04). No significant change after immunization was seen for interleukin-4 production. A significant increase in mean levels of HIV-1 antigen-stimulated RANTES (i.e., regulated upon, activation normal T-cell expressed and secreted), was evident 1 month after immunization (p = 0.002) and remained elevated 3 months after immunization. RANTES production was decreased in CD8-depleted PBMC cultures. Mean serum HIV-1 RNA copy numbers and CD4 cell counts remained stable after immunization (p > 0.5). A correlation was demonstrated between HIV-1 antigen-stimulated interferon-gamma and RANTES production (r = 0.54, p = 0.002).

CONCLUSIONS

This report describes an augmentation of beta-chemokines and TH1-type cytokines from PBMCs after immunization with the HIV-1 immunogen.

Biochemical characterization of recombinant fusions of lipopolysaccharide binding protein and bactericidal/permeability-increasing protein. Implications in biological activity

The physiological response to endotoxin (lipopolysaccharide (LPS)) can be regulated by two closely related LPS-binding proteins, LPS-binding protein (LBP), which potentiates LPS' inflammatory activity via interaction with the monocytic antigen CD14, and bactericidal/permeability-increasing protein (BPI), which neutralizes LPS. Both proteins bind LPS with high affinity sites in their N-terminal domains, whereas interaction between LBP and CD14 is dependent upon the LBP C-terminal domain. We have created fusions of the N- and C-terminal domains from each protein and compared the functional activities and pharmacokinetics of these fusions, the individual N-terminal domains, and the parent proteins. The N-terminal domains of BPI and LBP bound lipid A with their characteristic apparent affinity constants, regardless of the C-terminal fusion partner. In addition, the C-terminal domain of LBP allowed transfer of LPS to CD14 in conjunction with either N-terminal LPS binding domain. Proteins containing a BPI N-terminal domain had greater heparin binding capacities in vitro and were cleared more rapidly from the plasma of whole animals. Taken together, these data better define how closely related proteins such as BPI and LBP can have opposing effects on the body's response to LPS.

Expression and characterization of cysteine-modified variants of an amino-terminal fragment of bactericidal/permeability-increasing protein

rBPI23 is a biologically active, recombinant N-terminal fragment of human bactericidal/permeability-increasing protein (BPI). While rBPI23 is readily purified from culture supernatants of Chinese hamster ovary (CHO)-K1 transfectants, it is heterogeneous, consisting of monomer and disulfide-linked dimer, characteristics due presumably to the presence of three cysteines within the molecule. We have examined the role of these cysteines in rBPI23 expression, function, and dimer formation by mutating their codons to alanine (C132A), serine (C135S), or alanine (C175A) and expressing analogues of N-terminal fragments ("variants") lacking one, two, or all three cysteines in permanently transfected CHO-K1 cells. We also expressed a variant in which serine 18 was changed to cysteine (S18C), as found in both bovine and rabbit BPI. The C132A variant was readily secreted and purified as a homogeneous, stable monomeric protein species. The C135S and S18C variants were produced as mixtures of monomer and dimer; the C135S variant was poorly secreted, difficult to purify, and unstable on storage. In contrast, the C175A variant and those lacking any two or all three cysteines were expressed but not secreted. Purified rBPI23 and the C132A and S18C variants had comparable bactericidal and lipopolysaccharide (LPS) binding activities and were similarly effective at neutralizing LPS-induced tumor necrosis factor synthesis by THP-1 cells; the purified C135S variant lacked all activities. From these studies with CHO-K1 transfectants, we conclude that (i) cysteines 135 and 175 are both necessary for efficient secretion of a biologically active N-terminal BPI fragment, presumably through the formation of a disulfide bond, (ii) cysteine 132 is responsible for dimer formation, and (iii) only the C132A modification yields a stable, biologically active, N-terminal BPI fragment (designated rBPI21) that is free of dimeric species.

Monocyte tissue factor induction by lipopolysaccharide (LPS): dependence on LPS-binding protein and CD14, and inhibition by a recombinant fragment of bactericidal/permeability-increasing protein

Mononuclear phagocytes, stimulated by bacterial lipopolysaccharide (LPS), have been implicated in the activation of coagulation in sepsis and endotoxemia. In monocytes LPS induces the synthesis of tissue factor (TF) which, assembled with factor VII, initiates the blood coagulation cascades. In this study we investigated the mechanism of LPS recognition by monocytes, and the consequent expression of TF mRNA and TF activity. We also studied the inhibition of these effects of LPS by rBPI23, a 23-kD recombinant fragment of bactericidal/permeability increasing protein, which has been shown to antagonize LPS in vitro and in vivo. Human peripheral blood mononuclear cells, or monocytes isolated by adherence, were stimulated with Escherichia coli O113 LPS at physiologically relevant concentrations (> or = 10 pg/mL). The effect of LPS was dependent on the presence of the serum protein LBP (lipopolysaccharide-binding protein), as shown by the potentiating effect of human recombinant LBP or serum. Furthermore, recognition of low amounts of LPS by monocytes was also dependent on CD14 receptors, because monoclonal antibodies against CD14 greatly reduced the LPS sensitivity of monocytes in the presence of serum or rLBP. Induction of TF activity and mRNA expression by LPS were inhibited by rBPI23. The expression of tumor necrosis factor showed qualitatively similar changes. Considering the involvement of LPS-induced TF in the potentially lethal intravascular coagulation in sepsis, inhibition of TF induction by rBPI23 may be of therapeutic benefit.

An amino-terminal fragment of human lipopolysaccharide-binding protein retains lipid A binding but not CD14-stimulatory activity

LPS-binding protein (LBP) mediates the pro-inflammatory effects of bacterial LPS by enhancing LPS-induced cytokine production by monocytic cells. LBP binds specifically to LPS to generate a complex that interacts with the CD14 receptor on the surface of responsive cells. To identify the biologically active regions of the protein responsible for mediating these activities, we cloned and expressed human rLBP (456 amino acids) as well as a truncated form encoding amino acids 1-197 (rLBP25). Both forms of LBP bound to LPS with the same affinity, and similarly inhibited LPS activity in the Limulus amebocyte lysate assay. These results demonstrate that the LPS-binding domain of LBP resides entirely within the N-terminal 197 amino acids of the protein. rLBP and rLBP25 were compared for their ability to mediate CD14-dependent LPS effects on cells. rLBP was effective in mediating uptake of LPS and stimulation of TNF production by human monocytic THP-1 cells, whereas rLBP25 had no significant activity in these assays. Similarly, rLBP was able to mediate LPS-induced TNF production by human PBMC whereas rLBP25 was essentially inactive. These results suggest that the structural features of LBP required for mediating LPS effects via CD14 are probably located in the C-terminal region of the protein. Thus, the LPS-binding activity of LBP can be separated from the CD14-stimulatory activity, suggesting these activities are mediated by structural elements residing in different regions of the protein.

Competition between rBPI23, a recombinant fragment of bactericidal/permeability-increasing protein, and lipopolysaccharide (LPS)-binding protein for binding to LPS and gram-negative bacteria

Lipopolysaccharide (LPS)-binding protein (LBP) and bactericidal/permeability-increasing protein (BPI) are two structurally related lipid A-binding proteins with divergent functional activities. LBP mediates activation of macrophage and other proinflammatory cells. In contrast, BPI has potent bactericidal and LPS-neutralizing activities. A recombinant fragment of BPI (rBPI23) retains the potent biological activities of the holo protein and may represent a novel therapeutic agent for the treatment of gram-negative infections, sepsis, and endotoxemia. For therapeutic effectiveness in many clinical situations, rBPI23 will have to successfully compete with high serum levels of LBP for binding to endotoxin and gram-negative bacteria. The relative binding affinities of rBPI23 and human recombinant LBP (rLBP) for lipid A and gram-negative bacteria were evaluated. The binding of both proteins to lipid A was specific and saturable with apparent Kds of 2.6 nM for rBPI23 and 58 nM for rLBP. rBPI23 was approximately 75-fold more potent than rLBP in inhibiting the binding of 125I-rLBP to lipid A. The binding affinity of rBPI23 (Kd = 70 nM) for Escherichia coli J5 bacteria was also significantly higher than that of rLBP (Kd = 1,050 nM). In addition, rBPI23 at 0.2 micrograms/ml was able to inhibit LPS-induced tumor necrosis factor release from monocytes in the presence of 20 micrograms of rLBP per ml. These results demonstrate that rBPI23 binds more avidly to endotoxin than does rLBP and that, even in the presence of a 100-fold weight excess of rLBP, rBPI23 effectively blocks the proinflammatory response of peripheral blood mononuclear cells to endotoxin.

An amino-terminal fragment of human lipopolysaccharide-binding protein retains lipid A binding but not CD14-stimulatory activity

LPS-binding protein (LBP) mediates the pro-inflammatory effects of bacterial LPS by enhancing LPS-induced cytokine production by monocytic cells. LBP binds specifically to LPS to generate a complex that interacts with the CD14 receptor on the surface of responsive cells. To identify the biologically active regions of the protein responsible for mediating these activities, we cloned and expressed human rLBP (456 amino acids) as well as a truncated form encoding amino acids 1-197 (rLBP25). Both forms of LBP bound to LPS with the same affinity, and similarly inhibited LPS activity in the Limulus amebocyte lysate assay. These results demonstrate that the LPS-binding domain of LBP resides entirely within the N-terminal 197 amino acids of the protein. rLBP and rLBP25 were compared for their ability to mediate CD14-dependent LPS effects on cells. rLBP was effective in mediating uptake of LPS and stimulation of TNF production by human monocytic THP-1 cells, whereas rLBP25 had no significant activity in these assays. Similarly, rLBP was able to mediate LPS-induced TNF production by human PBMC whereas rLBP25 was essentially inactive. These results suggest that the structural features of LBP required for mediating LPS effects via CD14 are probably located in the C-terminal region of the protein. Thus, the LPS-binding activity of LBP can be separated from the CD14-stimulatory activity, suggesting these activities are mediated by structural elements residing in different regions of the protein.

A recombinant amino terminal fragment of bactericidal/permeability-increasing protein inhibits the induction of leukocyte responses by LPS

Bactericidal/permeability-increasing protein (BPI) is a major component of the granules of polymorphonuclear neutrophils (PMNs) and is involved in the killing of gram-negative bacteria. A 23-kd recombinant protein, corresponding to the NH2-terminal fragment of human BPI (rBPI23), has been shown to bind lipid A and antagonize some lipopolysaccharide (LPS)-mediated effects. In this study the ability of rBPI23 to prevent a wide range of cellular responses to LPS was investigated. In vitro assays were carried out using human blood to more closely approximate in vivo conditions. The release of proinflammatory cytokines [tumor necrosis factor (TNF), interleukin-1 beta (IL-1 beta), IL-6, IL-8], induced by E. coli O113 LPS, was markedly reduced by rBPI23 in a concentration-dependent fashion. The production of the anti-inflammatory protein IL-1ra (IL-1 receptor antagonist) was triggered by lower LPS concentrations than those necessary for the other cytokines. Furthermore, prevention of IL-1ra release required higher rBPI23 concentrations than for other cytokines. The LPS-induced production of oxygen-derived free radicals by phagocytic cells (resulting in chemiluminescence) was also prevented by rBPI23. The inhibition was specific for LPS because the activation of leukocytes by phorbol myristate acetate, zymosan, or TNF was unaffected by BPI. The ability of rBPI23 to antagonize specifically the effects of endotoxin in the complex environment of human blood along with its bactericidal activity suggests that rBPI23 may be a novel therapeutic agent in the treatment of gram-negative infections.

Protective effect of a recombinant amino-terminal fragment of bactericidal/permeability-increasing protein in experimental endotoxemia

Bactericidal/permeability-increasing protein (BPI), a cationic protein found in neutrophil granules, binds with high affinity to gram-negative bacterial lipopolysaccharide (LPS) and can inhibit its actions in vitro. The in vivo efficacy of a recombinant 23-kDa amino-terminal LPS-binding fragment of BPI (rBPI23) was assessed in a mouse model of lethal endotoxemia. Systemic administration of rBPI23 protected actinomycin D-sensitized mice from lethal LPS (Escherichia coli O111:B4) challenge in a dose-dependent manner, with almost complete protection at the highest dose (10 mg/kg; 93% survival vs. 13% in vehicle-treated controls). Surviving rBPI23-treated animals did not show histopathologic signs of tissue damage evident in control animals that had died after LPS challenge. rBPI23 also attenuated the LPS-induced elevation in serum levels of tumor necrosis factor-alpha and interleukin-1 alpha, mediators believed to be involved in the pathogenesis of endotoxemia and sepsis. Thus, rBPI23 may be a potential new therapeutic agent for the treatment of gram-negative bacterial infection and sepsis.

High-affinity binding of the bactericidal/permeability-increasing protein and a recombinant amino-terminal fragment to the lipid A region of lipopolysaccharide

Bactericidal/permeability-increasing protein (BPI) is a 55-kDa cationic protein (nBPI55) elaborated by polymorphonuclear neutrophils (PMN). BPI has potent bactericidal activity against a wide variety of gram-negative organisms and neutralizes endotoxin activities. An N-terminal fragment of nBPI55 exhibits the bactericidal and antiendotoxin properties of the holoprotein. To further characterize the biological activities of the N-terminal fragment, a recombinant protein (rBPI23) corresponding to the first 199 amino acids of human BPI was produced and purified. rBPI23 had antibacterial activity equivalent to that of nBPI55 against Escherichia coli J5. Furthermore, both rBPI23 and nBPI55 bound identically to a broad range of R- and S-form lipopolysaccharides (LPS) and to natural and synthetic lipid A. Binding of radiolabeled nBPI55 to LPS was inhibited in an identical fashion by either nBPI55 or rBPI23. The binding of both proteins to immobilized E. coli J5 lipid A was inhibited in a comparable fashion by long- or short-chain LPS or lipid A. The binding of both rBPI23 and nBPI55 was specific, saturable, and of high affinity, with an apparent Kd of approximately 2 to 5 nM for all ligands tested. These results demonstrate that BPI recognizes the highly conserved lipid A region of bacterial LPS via residues contained within the amino-terminal portion of the BPI molecule.

Human bactericidal/permeability-increasing protein and a recombinant NH2-terminal fragment cause killing of serum-resistant gram-negative bacteria in whole blood and inhibit tumor necrosis factor release induced by the bacteria

The bactericidal/permeability-increasing protein (BPI) of neutrophils and BPI fragments neutralize the effects of isolated Gram-negative bacterial lipopolysaccharides both in vitro and in vivo. Since endotoxin most commonly enters the host as constituents of invading Gram-negative bacteria, we raised the question: Can BPI and its bioactive fragments also protect against whole bacteria? To determine whether the bactericidal and endotoxin-neutralizing activities of BPI/fragments are expressed when Gram-negative bacteria are introduced to the complex environment of whole blood we examined the effects of added BPI and proteolytically prepared and recombinant NH2-terminal fragments on: (a) the fate of serum-resistant encapsulated Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa that survive the antibacterial actions of whole blood and (b) the ability of these bacteria to trigger cytokine release. Added BPI in nanomolar concentrations killed each of three encapsulated strains of E. coli and in closely parallel fashion inhibited tumor necrosis factor (TNF) release. Holo-BPI and its NH2-terminal fragment were equipotent toward a rough LPS chemotype K1-encapsulated strain, but the fragment was substantially more potent than holo-BPI toward two encapsulated smooth LPS chemotype strains. TNF release induced by K. pneumoniae and P. aeruginosa was also inhibited by both holo-BPI and fragment but, at the protein concentrations tested, P. aeruginosa was killed only by the fragment and K. pneumoniae was not killed by either protein. The bactericidal action of BPI/fragment toward E. coli is inhibited by C7-depleted serum, but accelerated by normal serum, indicating that BPI, acting in synergy with late complement components, enhances extracellular killing of serum-resistant bacteria. Thus, BPI and an even more potent NH2-terminal fragment may protect against Gram-negative bacteria in the host by blocking bacterial proliferation as well as endotoxin-mediated effects, not only as components of the intracellular antibacterial arsenal of the neutrophil, but also as potentially therapeutic extracellular agents.

Molecular structure of the rat bone Gla protein gene and identification of putative regulatory elements

The rat bone Gla protein (BGP, osteocalcin) gene was isolated from a rat genomic library and sequenced. BGP is a 5.8-kD noncollagenous protein secreted by calcified tissues whose expression is regulated by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. The BGP gene consists of 4 exons separated by 3 introns and spans almost 1 kb of DNA. The 5'-flanking region of the gene contains CCAAT and TATAAA elements common to eukaryotic genes. An analysis of approximately 600 bp of 5'-flanking sequence of this gene revealed sequences homologous to regulatory elements for glucocorticoids, metal ions, and cAMP. The latter is especially significant since recent evidence suggests that the rat BGP gene can be regulated by cAMP. This region of the gene also contains numerous pairs of inverted repeat sequences (imperfect palindromes). The sequence of the rat BGP gene was compared to that of the recently published human BGP gene (Celeste et al., EMBO J. 5, 1885, 1986). The coding regions of these two genes share 77% sequence identity, and several regions of the 5'-flanking sequences are also well conserved. Knowledge of the sequence of the rat BGP gene will allow studies of its regulation by 1,25(OH)2D3, cAMP, and other trans-acting transcriptional factors, and identification of the regulatory sequence elements involved.

Bone Gla protein messenger ribonucleic acid is regulated by both 1,25-dihydroxyvitamin D3 and 3',5'-cyclic adenosine monophosphate in rat osteosarcoma cells

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] regulates the synthesis of bone gamma-carboxyglutamic acid (Gla) protein (BGP) by osteoblastic cells. In this study we examined the effect of cAMP, alone and in combination with 1,25-(OH)2D3, on the regulation of BGP mRNA levels in ROS 17/2 rat osteosarcoma cells. Elevation of intracellular cAMP levels by cAMP analogs or by isobutylmethylxanthine (IBMX), forskolin, or PTH, resulted in increased BGP mRNA levels and BGP secretion after 1 day of treatment. The effects of these agents were additive with 1,25-(OH)2D3 in stimulating BGP gene expression. After 4 days of treatment, pertussis toxin (PT) and 1,25-(OH)2D3 were synergistic in stimulating BGP mRNA, and the effect of PT could be mimicked by (Bu)2cAMP, IBMX, forskolin, cholera toxin, and to a lesser extent by PTH. The effect of 1-day treatment with cAMP alone and the synergistic effect with 1,25-(OH)2D3 on the stimulation of BGP mRNA were dependent on cell density, while basal and 1,25-(OH)2D3-stimulated synthesis were not. Cyclic AMP inhibited ROS 17/2 cell growth after 1 day of treatment, an effect that was also dependent on initial cell density. After 4 days of treatment, 1,25-(OH)2D3, cAMP, and PT all demonstrated inhibition of cell growth. When cells were treated with actinomycin D, both 1,25-(OH)2D3 and cAMP stimulation of BGP mRNA were blocked. In addition, neither agent was effective in enhancing BGP mRNA stability when prestimulated cells were exposed to actinomycin D.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular structure of the chicken vitamin D-induced calbindin-D28K gene reveals eleven exons, six Ca2+-binding domains, and numerous promoter regulatory elements

The seco-steroid hormone 1,25-dihydroxyvitamin D3 is known to induce the expression of a calcium binding protein termed calbindin-D28K in a variety of target tissues. In order to comprehend the mechanism of induction we have cloned and sequenced the chicken calbindin-D28K gene. The gene spans some 18.5 kilobases (kb) of chromosomal DNA from the putative Cap site to the polyadenylation site of the 2.8 kb mRNA. It is split into 11 coding exons by 10 intervening sequences. The promoter region of this gene is markedly G + C-rich (60-80%) extending from -225 to +400. Within this region we find 70 CpG dinucleotides, four G-C boxes, and numerous known promoter regulatory signals. These putative regulatory signals include a TATA box (ATAAATA) at -30 and a CAT box (CCAAT) at -326. Ten additional variant CAT boxes are found in the upstream promoter region (-218 to -770) of this gene. Furthermore we have identified a glucocorticoid-like responsive element at -410 (TCTACACACTGTTCC) and this element overlaps a metal responsive element (TGCACTC) and a variant CAT box (CCAAAT) and juxtaposes an enhancer-like core element (AAATGGT) on its 3'-side. In addition, the calbindin-D28K promoter is composed of a variety of simple repeated sequences, some of which are components of putative regulatory signals. All splice junctions were found to conform to the GT-AG rule. A consensus sequence of the 5'-splice junction reads AG/GTAAG-TTATA. A consensus sequence of the 3'-splice site consists of two elements: a pyrimidine track (mainly T) followed by ACAG/G-T. A two-dimensional model of calbindin-D28K was constructed which projects the existence of 6 alpha-helix-loop-alpha-helix regions characteristic of calcium binding domains. The 3'-end of the gene consists of a single large (2039 base pair) uninterrupted exon, an organizational feature common to other members of the calcium binding protein gene family which include calmodulin, parvalbumin, Spec I, myosin light chains, etc. Another feature common to the gene family is the presence of the repeated sequence ATTT or TTTA located in the 3'-untranslated exons. These simple repeat sequences could be involved in regulating mRNA degradation by serving as a ribonuclease recognition signal.

Expression of calbindin-D28K mRNA as a function of altered serum calcium and phosphorus levels in vitamin D-replete chick intestine

The availability of specific cDNA probes to the chick intestinal calbindin-D28K (CaBP) mRNA has allowed us to assess the regulation of this mRNA in response to 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) administration. It has previously been demonstrated that dietary calcium and phosphorus can effect alterations in the steady-state intestinal levels of chick CaBP. We have examined whether or not perturbations in dietary calcium and phosphorus have an effect on the expression of the intestinal mRNA coding for CaBP in the vitamin D-replete chick. We found altered protein levels of CaBP as expected; however there was surprisingly no difference in steady-state CaBP mRNA levels between the different dietary groups. These data suggest that calcium and phosphorus regulation of CaBP occurs at a post-transcriptional level. In addition, we have examined what effect dietary manipulations of calcium and phosphorus levels have on the response of the vitamin D-replete intestine to 1,25(OH)2D3 administration as assessed by CaBP mRNA changes. Administration of 1,25(OH)2D3 to vitamin D-replete chicks maintained on normal calcium and phosphorus levels resulted in a less than 2-fold increase in CaBP mRNA levels. Previous studies have demonstrated that receptor occupancy goes up 6-fold under these conditions; therefore there is apparently a very tight regulation of CaBP gene activity. 1,25(OH)2D3 administration to chicks raised on either low calcium, high calcium, or low phosphorus vitamin D-replete diets similarly showed only small changes in the intestinal CaBP mRNA levels; however there seemed to be qualitative differences in response attributable to the dietary alterations.

1,25-Dihydroxyvitamin D3 regulates tubulin expression in chick intestine

As in many other cell types, autoregulation of tubulin synthesis is evident in the intestinal epithelium of normal (vitamin D-replete) chicks: Suppression of protein (tubulin) synthesis by cycloheximide administration in vivo resulted within 30 min in a two-fold increase in RNA hybridizing with an alpha-tubulin probe. Vitamin D status revealed an additional regulatory component. alpha-Tubulin mRNA was elevated in vitamin D-deficient (-D) chicks and those treated with 1,25(OH)2D3 for 1-10 h prior to sacrifice, but declined precipitously 15-20 h after hormone, and in normal birds. These results suggested hormonally increased tubulin levels which in turn suppressed cellular alpha-tubulin mRNA. Analyses of total tubulin levels by [3H]-colchicine binding revealed low levels of the protein(s) in -D chicks, increased levels at 1-15 h after 1,25(OH)2D3, and maximum binding at 20 h after hormone and in normal birds.

Regulation of calbindin-D28K gene expression by 1,25-dihydroxyvitamin D3 is correlated to receptor occupancy

1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3) induces the synthesis of calcium binding protein (calbindin-D28K) and calbindin-D28K-mRNA in the chick intestine. We have examined the relationship between nuclear uptake of 1,25-(OH)2D3, 1,25-(OH)2D3 receptor occupancy levels, and transcription of the calbindin-D28K gene and found all three parameters to be highly correlated. All three events occur rapidly (within 15-30 min) following a single dose of 6.5 nmol of 1,25-(OH)2D3 to vitamin D-deficient chicks, reaching peak values by 1-2 h; by 4 h, values of all three parameters start to decline. Calbindin-D28K-mRNA begins to accumulate by 3-5 h but does not peak until 12 h following hormone administration. The levels of calbindin-D28K start to increase by 5-8 h and do not peak until 48 h after the 1,25-(OH)2D3 dose. These observations suggest that post-transcriptional regulatory mechanisms may be involved. Measurements of basal levels of calbindin-D28K gene transcription show that there is virtually no transcription in the vitamin D-deficient chick intestine, and a 12-fold induction in the intestine of vitamin D-replete chicks. This basal level of transcription in vitamin D-replete chick intestine is not inhibited by cycloheximide pretreatment. These results confirm the thesis that a major component of the mechanism of action of 1,25-(OH)2D3 is functioning as a steroid hormone, effected through the direct action of the seco-steroid-receptor complex on the initiation of transcription of specific genes.

Effects of alpha-amanitin and cycloheximide on 1,25-dihydroxyvitamin D3-dependent calbindin-D28K and its mRNA in vitamin D3-replete chick intestine

We have examined the effects of the transcriptional inhibitor alpha-amanitin and the translational inhibitor cycloheximide on levels of calbindin-D28K (28-kDa calcium binding protein, CaBP) and CaBP-mRNA in the vitamin D-replete chick intestine. Chicks were raised on one of four diets: "normal" (1% calcium, 0.6% phosphorus); high calcium (3.3% calcium, 0.5% phosphorus); low calcium (0.3% calcium, 0.6% phosphorus); or low phosphorus (1% calcium, 0.09% phosphorus). Chicks were then treated either with alpha-amanitin (20 micrograms/chick) or cycloheximide (600 micrograms/chick) 2 h prior to a dose of 6.5 nmol of 1,25-dihydroxyvitamin D3. Duodenal mucosa was collected from 0 to 120 min afterward and assayed for CaBP-mRNA by dot blot hybridization and for CaBP using an enzyme-linked immunosorbent assay. In the absence of inhibitor, CaBP levels were depressed by high calcium and elevated by low calcium or low phosphorus, as expected. These changes occurred, however, without a change in CaBP-mRNA levels. alpha-Amanitin had no effect on CaBP or on CaBP-mRNA levels in chicks raised on any of the diets. Cycloheximide inhibited CaBP levels, and surprisingly also inhibited CaBP-mRNA levels in all four dietary groups. These results indicate that continual protein synthesis is necessary for the expression of CaBP-mRNA, suggesting the existence of a rapidly turned over protein that may be required for stabilization or for processing of the chick intestinal CaBP messenger RNA.

Characterization of the calf uterine progesterone receptor and its stabilization by nucleic acids

The molecular and steroid hormone-binding properties of the calf uterine progesterone receptor and its interaction with nucleic acids were investigated. A positive cooperative binding interaction of [3H]progesterone with the receptor was evident from a nonlinear Scatchard plot and a Hill coefficient of 1.22 +/- 0.02. The range of progesterone receptor concentrations was 0.73-1.04 pmol/mg protein, approximately twice that of the estrogen receptor. Competitive binding assays revealed a high specificity for progesterone: R5020 greater than or equal to progesterone greater than deoxycorticosterone greater than 5 alpha-pregnane-3,20-dione much greater than 17 alpha-hydroxyprogesterone greater than or equal to 20 alpha-dihydroprogesterone greater than or equal to testosterone greater than or equal to estradiol greater than cortisol. Thus, a progesterone-specific receptor of high affinity and concentration is obtainable from calf uterus in large quantities without estrogen pretreatment. Thermal inactivation of the unoccupied progesterone receptor is inhibited by 10 mM sodium molybdate, whereas thermal inactivation of the ammonium sulfate-purified progesterone receptor is not. Thermal inactivation of the ammonium sulfate-purified receptor is inhibited by nucleic acids and polynucleotides; polyguanylate (poly G) is the most effective. DNA and poly G also effectively restore the progesterone-binding ability of the ammonium sulfate-purified receptor which had been lost due to heat inactivation. After incubation of the unoccupied receptor from 5-30 min at 25 C, the addition of poly G restored the receptor's [3H]progesterone-binding ability to control levels. These data suggest that the progesterone receptor's steroid-binding site is more readily inactivated by heat than is the DNA-binding site, and that nucleic acid binding induces a conformational change, which consequently restores the receptor's progesterone-binding site to functional activity.

The in vitro synthesis of final maturational steroids by ovaries of brook trout (Salvelinus fontinalis) and yellow perch (Perca flavescens)

The steroidogenic profile produced by ovaries of brook trout (Salvelinus fontinalis) and yellow perch (Perca flavescens) was examined using radioactive incorporation incubations. The radioactive metabolites produced were identified and were tested for their ability to induce germinal vesicle breakdown (GVBD) in oocytes in in vitro bioassays. Brook trout ovarian tissue converted [14C]progesterone to five metabolites that were effective in inducing GVBD in the bioassays: 5 beta-pregnanedione, 17 alpha-hydroxyprogesterone, deoxycorticosterone, and two more polar metabolites that were not identified. One of these two metabolites comigrated with 11-deoxycortisol and 17 alpha-hydroxy,20 beta-dihydroprogesterone (17 alpha, 20 beta prog) in thin layer chromatography. Androstenedione, testosterone, and estradiol-17 beta were also identified as metabolites of progesterone. Brook trout ovarian tissue did not extensively metabolize [14C]pregnenolone. Dehydroepiandrosterone and 17 alpha-hydroxypregnenolone were tentatively identified as metabolites of pregnenolone. Yellow perch ovarian tissue converted [14C]progesterone or [14C]pregnenolone to six metabolites that were effective in inducing GVBD in the bioassays: 5 alpha-pregnanedione, 17 alpha-hydroxyprogesterone, 20 alpha-dihydroprogesterone, 17 alpha-hydroxy, 20 alpha-dihydroprogesterone (tentatively identified), and two other unidentified metabolites. One of these two metabolites comigrated with 11-deoxycortisol and 17 alpha, 20 beta prog in thin layer chromatography. The only metabolite that induced ovulation of yellow perch oocytes in vitro was the metabolite comigrating with 11-deoxycortisol and 17 alpha, 20 beta prog. Androstenedione and testosterone were also identified as metabolites produced by yellow perch ovarian tissue. The results show that the ovaries of both species produce steroids that are active in the induction of oocyte final maturation.