Structural stability of Burkholderia cenocepacia biofilms is reliant on eDNA structure and presence of a bacterial nucleic acid binding protein

Cystic fibrosis (CF) is the most common lethal inherited genetic disorder affection Caucasians. Even with medical advances, CF is life-shortening with patients typically surviving only to age 38. Infection of the CF lung by Burkholderia cenocepacia presents exceptional challenges to medical management of these patients as clinically this microbe is resistant to virtually all antibiotics, is highly transmissible and infection of CF patients with this microbe renders them ineligible for lung transplant, often the last lifesaving option. Here we have targeted two abundant components of the B. cenocepacia biofilm for immune intervention: extracellular DNA and DNABII proteins, the latter of which are bacterial nucleic acid binding proteins. Treatment of B. cenocepacia biofilms with antiserum directed at one of these DNABII proteins (integration host factor or IHF) resulted in significant disruption of the biofilm. Moreover, when anti-IHF mediated destabilization of a B. cenocepacia biofilm was combined with exposure to traditional antibiotics, B. cenocepacia resident within the biofilm and thereby typically highly resistant to the action of antibiotics, were now rendered susceptible to killing. Pre-incubation of B. cenocepacia with anti-IHF serum prior to exposure to murine CF macrophages, which are normally unable to effectively degrade ingested B. cenocepacia, resulted in a statistically significant increase in killing of phagocytized B. cenocepacia. Collectively, these findings support further development of strategies that target DNABII proteins as a novel approach for treatment of CF patients, particularly those whose lungs are infected with B. cenocepacia.

Pathogenic complement activation in collagen antibody-induced arthritis in mice requires amplification by the alternative pathway

Immune complex-induced inflammation can be mediated by the classical pathway of complement. However, using mice genetically deficient in factor B or C4, we have shown that the collagen Ab-induced model of arthritis requires the alternative pathway of complement and is not dependent on the classical pathway. We now demonstrate that collagen Ab-induced arthritis is not altered in mice genetically deficient in either C1q or mannose-binding lectins A and C, or in both C1q and mannose-binding lectins. These in vivo results prove the ability of the alternative pathway to carry out pathologic complement activation in the combined absence of intact classical and lectin pathways. C3 activation was also examined in vitro by adherent collagen-anti-collagen immune complexes using sera from normal or complement-deficient mice. These results confirm the ability of the alternative pathway to mediate immune complex-induced C3 activation when C4 or C1q, or both C1q and mannose-binding lectins, are absent. However, when all three activation pathways of complement are intact, initiation by immune complexes occurs primarily by the classical pathway. These results indicate that the alternative pathway amplification loop, with its ability to greatly enhance C3 activation, is necessary to mediate inflammatory arthritis induced by adherent immune complexes.

CTL-associated antigen-4 ligation induces rapid T cell polarization that depends on phosphatidylinositol 3-kinase, Vav-1, Cdc42, and myosin light chain kinase

CTLA-4 can negatively regulate cytokine production and proliferation, increase motility, and override the TCR-induced stop-signal needed for stable T cell-APC conjugation. Despite this, little is known regarding whether CTLA-4 can alter T cell morphology and the nature of the signaling events that could account for this event. In this study, we demonstrate that anti-CTLA-4 and CD3/CTLA-4 induce rapid T cell polarization (i.e., within 15-30 min) with increases in lamellipodia, filopodia, and uropod formation. This was observed with anti-CTLA-4 and CD80-Ig ligation of CTLA-4, but not with anti-CD3 alone, or anti-CD3/CD28 coligation. Polarization required PI3K, the guanine nucleotide exchange factor Vav1, the GTP-binding protein Cdc42, as well as myosin L chain kinase. By contrast, a key downstream target of PI3K, protein kinase B, as well as Rho kinase and RhoA, were not needed. Our results demonstrate that CTLA-4 is a potent activator T cell polarization needed for motility, and this process involves specific set of signaling proteins that might contribute to coreceptor regulation of T cell function.

Role of eIF3a (eIF3 p170) in intestinal cell differentiation and its association with early development

Eukaryotic initiation factor 3a (eIF3a) has been suggested to play a regulatory role in mRNA translation. Decreased eIF3a expression has been observed in differentiated cells while higher levels have been observed in cancer cells. However, whether eIF3a plays any role in differentiation and development is currently unknown. Here, we investigated eIF3a expression during mouse development and its role in differentiation of colon epithelial cells. We found that eIF3a expression was higher in fetal tissues compared with postnatal ones. Its expression in intestine, stomach, and lung abruptly stopped on the 18th day in gestation but persisted in liver, kidney, and heart throughout the postnatal stage at decreased levels. Similarly, eIF3a expression in colon cancer cell lines, HT-29 and Caco-2, drastically decreased prior to differentiation. Enforced eIF3a expression inhibited while knocking it down using small interference RNA promoted Caco-2 differentiation. Thus, eIF3a may play some roles in development and differentiation and that the decreased eIF3a expression may be a pre-requisite of intestinal epithelial cell differentiation.

Fimch antiserum inhibits the adherence of Escherichia coli to cells collected by voided urine specimens of diabetic women

PURPOSE

With the increasing problem of resistance in pathogenic microorganisms the development of nonantimicrobial therapies is important. Diabetes mellitus (DM) is associated with an increased incidence of urinary tract infections. The majority of Escherichia coli strains, which is the most prevalent uropathogen, have type 1 fimbriae that bind to uroplakin in the bladder, as mediated by the adhesin FimH. A vaccine is being developed based on FimH adhesion.

MATERIALS AND METHODS

The sequence of FimH adhesion of 29 E. coli strains isolated from women with DM was determined. For adherence experiments we used E. coli isolated from women with DM and a T24 bladder cell line as well as the 2 well-defined type 1 fimbriated E. coli strains Ctrl 39 and NU14, and uroepithelial cells from women with DM.

RESULTS

The fimH sequence of E. coli strains isolated from women with DM was highly homologous to the known fimH sequence of E. coli from patients without DM. Adherence assays in a T24 bladder cell line showed that adherence of these E. coli strains from women with DM could be inhibited by pre-incubation with antiserum raised against the chaperone-adhesin complex FimC-FimH. AntiFimCH antiserum also inhibited the adherence of the 2 well-defined E. coli strains expressing type 1 fimbriae, NU14 and Ctrl 39, but not of the FimH mutant strain NU14 H-, to uroepithelial cells from women with DM.

CONCLUSIONS

These findings suggest that a vaccine based on FimH adhesin of type 1 fimbriated E. coli is a potential method of preventing urinary tract infection in women with DM.

Cutting edge: SDS-stable Fas microaggregates: an early event of Fas activation occurring with agonistic anti-Fas antibody but not with Fas ligand

The 45 kDa Fas or CD95 receptor triggers apoptosis via the caspase cascade when stimulated by its ligand FasL or by agonistic Abs. Activated Fas receptors seem to oligomerize very early into SDS-stable and reducing agent-resistant microaggregates of 200-250 kDa on SDS-PAGE. However, these microaggregates have so far only been reported using agonistic anti-Fas Abs, and no results have been reported using FasL. Here, we demonstrate that the microaggregates do not form in response to FasL, while they always appear in response to the agonistic Ab, in four different cell lines and in normal lymphocytes from human blood. Therefore, the Fas microaggregates are not required for the induction of apoptosis via FasL. These results also suggest that subtle differences exist in the apoptotic pathways triggered by anti-Fas agonistic Abs and by FasL.

A Switch in Costimulation from CD28 to 4-1BB during Primary versus Secondary CD8 T Cell Response to Influenza In Vivo

4-1BBL(-/-) mice exhibit normal primary CD8 T cell responses to influenza virus, but show decreased CD8 T cell numbers late in the primary response as well as decreased secondary responses. In contrast, CD28(-/-) mice are defective in initial CD8 T cell expansion. Using agonistic anti-4-1BB Ab to replace the CD28 or 4-1BB signal, we examined the timing of the required signals for CD28 vs 4-1BB costimulation. A single dose of agonistic anti-4-1BB Ab added only during priming restores the secondary CD8 T cell response in CD28(-/-) mice. Once the T cell numbers in the primary response reach a minimum threshold, a full secondary response is achieved even in the absence of CD28. In contrast, anti-4-1BB added during priming fails to correct the defective secondary response in 4-1BBL(-/-) mice, whereas addition of anti-4-1BB during challenge fully restores this response. Thus, there is a switch in costimulatory requirement from CD28 to 4-1BB during primary vs recall responses. Adoptive transfer studies show that T cells primed in 4-1BBL(-/-) or wild-type mice are equally capable of re-expansion when rechallenged in wild-type mice. These studies rule out a model in which signals delivered through 4-1BB during priming program the T cells to give a full recall response and suggest that 4-1BB-4-1BBL interactions take place at later stages in the immune response. The results indicate that anti-4-1BB or 4-1BBL therapy will be most effective during the boost phase of a prime-boost vaccination strategy.

Role of nerve growth factor in the regulation of parotid cell differentiation induced by rat serum

The present study was undertaken to examine the factors that regulate rat serum (RS)- and nerve growth factor (NGF)-induced differentiation in a rat parotid acinar cell line. RS elicited extracellular signal-regulated kinase (ERK1/ERK2) activation within 5min, while cyclic AMP (cAMP) levels transiently rose after 6hr. RS also elicited a rise in amylase mRNA levels within 30min, which preceded the rise in amylase protein levels. A possible role for NGF was suggested by the findings that parotid cells express both TrkA and p75 receptors. The immunoreactivity of these NGF receptors was reduced during exposure to RS. Following prolonged incubation in RS when ERK activity subsided to near basal levels, NGF restored ERK1/ERK2 activity to the elevated level initially observed in RS. NGF was ineffective when cells were incubated in fetal bovine serum. NGF, when incubated in combination with the cAMP-generating neuropeptides, calcitonin gene-related peptide and vasoactive intestinal peptide, markedly enhanced the cellular amylase content produced by RS. We conclude that parotid cell differentiation arises from an activation of cell surface receptors by humoral factors in combination with NGF and cAMP-generating neuropeptides.

IL-21 induces the apoptosis of resting and activated primary B cells

Cytokines play an important role in regulating the development and homeostasis of B cells by controlling their viability. In this study, we show that the recently described T cell-derived cytokine IL-21 induces the apoptosis of resting primary murine B cells. In addition, the activation of primary B cells with IL-4, LPS, or anti-CD40 Ab does not prevent IL-21-mediated apoptosis. The induction of apoptosis by IL-21 correlates with a down-regulation in the expression of Bcl-2 and Bcl-x(L), two antiapoptotic members of the Bcl-2 family. Furthermore, the reconstitution of Bcl-x(L) or Bcl-2 expression protects primary B cells from IL-21-induced apoptosis. In addition, a short-term preactivation of B cells with anti-CD40 Ab confers protection from IL-21-mediated apoptosis through the up-regulation of Bcl-x(L). These studies reveal a novel pathway that mediates B cell apoptosis via the IL-21R and suggest that IL-21 may play a role in regulating B cell homeostasis.

Cutting edge: selection of B lymphocyte subsets is regulated by natural IgM

Natural IgM has a wide range of actions in the immune system. Here we demonstrate that mice lacking serum IgM have an expansion in splenic marginal zone B cells with a proportionately smaller reduction in follicular B cells. The increase in the marginal zone-follicular B cell ratio (and an expansion in peritoneal B1a cells) is fully reversed by administration of polyclonal IgM, but not by two IgM monoclonals. Mice engineered to have a secreted oligoclonal IgM repertoire with an endogenous membrane IgM also exhibited a similar expansion of marginal zone B cells. We propose that natural IgM, by virtue of its polyreactivity, enhances Ag-driven signaling through the B cell receptor and promotes the formation of follicular B cells. These results demonstrate that natural IgM regulates the selection of B lymphocyte subsets.

Cutting edge: interactions through the IL-10 receptor regulate autoimmune diabetes

BDC2.5/nonobese diabetic (NOD) transgenic mice express a TCR from a diabetogenic T cell clone yet do not spontaneously develop diabetes at high incidence. Evidence exists showing that in the absence of endogenous TCR alpha-chain rearrangements this transgenic mouse spontaneously develops diabetes and that CTLA-4 negatively regulates diabetes onset. This strongly suggests that onset of diabetes in BDC2.5/NOD mice is governed by T cell regulation. We addressed the mechanism of immune regulation in BDC2.5/NOD mice. We find that activated spleen cells from young, but not old, BDC2.5/NOD mice are able to transfer diabetes to NOD-scid recipients. We have used anti-IL-10R to show that the failure of splenocytes from older mice to transfer diabetes is due to dominant regulation. We furthermore found that diabetes developed following anti-IL-10R treatment of 6-wk old BDC2.5/NOD mice indicating that endogenous IL-10 plays a key role in the regulation of diabetes onset in this transgenic mouse.

Signaling through TNF receptor p55 in TNF-alpha-deficient mice alters the CXCL13/CCL19/CCL21 ratio in the spleen and induces maturation and migration of anergic B cells into the B cell follicle

The organization of secondary lymphoid tissues into distinct T and B cell compartments supports proper regulation of an immune response to foreign Ags. In the splenic white pulp, this compartmentalization is also thought to be important in the maintenance of B cell tolerance. Using lymphotoxin-alpha-(LT-alpha)-, TNF-alpha-, or TNFRp55-deficient mice, all with disrupted splenic architecture, we tested whether normal T/B segregation and/or intact follicular structure are necessary for the maintenance of anti-dsDNA B cell anergy. This study demonstrates that anti-dsDNA B cells remain tolerant in LT-alpha(-/-), TNF-alpha(-/-), and TNFRp55(-/-) mice; however, TNF-alpha or a TNF-alpha-dependent factor is required for their characteristic positioning to the T/B interface. Providing a TNF-alpha signal in TNF-alpha(-/-) mice by systemic administration of an agonist anti-TNFRp55 mAb induces the maturation of the anti-dsDNA B cells and their movement away from the T cell area toward the B cell area. Additionally, the agonist Ab induces changes in the follicular environment, including FDC clustering, up-regulation of the CXC chemokine ligand CXCL13, and down-regulation of the CC chemokine ligands CCL19 and CCL21. Therefore, this study suggests that a balance between B and T cell tropic chemokine signals may be an important mechanism for positioning anergic B cells at the T/B interface of the splenic white pulp.

Role of chemokines and formyl peptides in pneumococcal pneumonia-induced monocyte/macrophage recruitment

Host-derived chemoattractant factors are suggested to play crucial roles in leukocyte recruitment elicited by inflammatory stimuli in vitro and in vivo. However, in the case of acute bacterial infections, pathogen-derived chemoattractant factors are also present, and it has not yet been clarified how cross-talk between chemoattractant receptors orchestrates diapedesis of leukocytes in this context of complex chemoattractant arrays. To investigate the role of chemokine (host-derived) and formyl peptide (pathogen-derived) chemoattractants in leukocyte extravasation in life-threatening infectious diseases, we used a mouse model of pneumococcal pneumonia. We found an increase in mRNA expression of eight chemokines (RANTES, macrophage-inflammatory protein (MIP)-1alpha, MIP-1beta, MIP-2, IP-10, monocyte chemoattractant protein (MCP)-1, T cell activation 3, and KC) within the lungs during the course of infection. KC and MIP-2 protein expression closely preceded pulmonary neutrophil recruitment, whereas MCP-1 protein production coincided more closely than MIP-1alpha with the kinetics of macrophage infiltration. In situ hybridization of MCP-1 mRNA suggested that MCP-1 expression started at peribronchovascular regions and expanded to alveoli-facing epithelial cells and infiltrated macrophages. Interestingly, administration of a neutralizing Ab against MCP-1, RANTES, or MIP-1alpha alone did not prevent macrophage infiltration into infected alveoli, whereas combination of the three Abs significantly reduced macrophage infiltration without affecting neutrophil recruitment. The use of an antagonist to N-formyl peptides, N-t-Boc-Phe-D-Leu-Phe-D-Leu-Phe, reduced both macrophages and neutrophils significantly. These data demonstrate that a complex chemokine network is activated in response to pulmonary pneumococcal infection, and also suggest an important role for fMLP receptor in monocyte/macrophage recruitment in that model.

Blockade of alpha 5 beta 1 integrins reverses the inhibitory effect of tenascin on chemotaxis of human monocytes and polymorphonuclear leukocytes through three-dimensional gels of extracellular matrix proteins

Tenascin is an extracellular matrix protein found in adults in T cell-dependent areas of lymphoid tissues, sites of inflammation, and tumors. We report here that it inhibited chemotaxis of chemoattractant-stimulated human monocytes and chemoattractant-stimulated polymorphonuclear leukocytes (PMN) through three-dimensional gels composed of collagen I or Matrigel, and chemotaxis of leukotriene B4-stimulated PMN through fibrin gels. The inhibitory effect of tenascin on monocyte or PMN chemotaxis through these matrices was reversed by Abs directed against alpha5beta1 integrins or by a peptide (GRGDSP) that binds to beta1 integrins. Tenascin did not affect leukotriene B4- or fMLP-stimulated expression of beta1 or beta2 integrins, but did exert a small inhibitory effect on PMN adhesion and closeness of apposition to fibrin(ogen)-containing surfaces. Thus, alpha5beta1 integrins mediate the inhibitory effect of tenascin on monocyte and PMN chemotaxis, without promoting close apposition between these leukocytes and surfaces coated with tenascin alone or with tenascin bound to other matrix proteins. This contrasts with the role played by alpha5beta1 integrins in promoting close apposition between fMLP-stimulated PMN and fibrin containing surfaces, thereby inhibiting chemotaxis of fMLP-stimulated PMN through fibrin gels. Thus, chemoattractants and matrix proteins regulate chemotaxis of phagocytic leukocytes by at least two different mechanisms: one in which specific chemoattractants promote very tight adhesion of leukocytes to specific matrix proteins and another in which specific matrix proteins signal cessation of migration without markedly affecting strength of leukocyte adhesion.

The murine IL-2 promoter contains distal regulatory elements responsive to the Ah receptor, a member of the evolutionarily conserved bHLH-PAS transcription factor family

Signaling through the TCR and costimulatory signals primarily control transcription of the IL-2 gene in naive T cells. The minimal promoter necessary for this expression lies proximal, between -300 and the transcription start site. We had previously shown that activation of the arylhydrocarbon receptor (AHR), a member of the bHLH-PAS family of transcription factors, leads to increased mRNA expression of IL-2 in murine fetal thymocytes. The AHR is abundant in the thymus and may play a role for the development of the immune system. Moreover, its overactivation by chemicals such as dioxins leads to immunosuppression and thymic involution. Binding motifs for the liganded AHR can be identified in the distal region -1300 to -800 of the mouse IL-2 promoter. We show here that these DNA motifs, the so-called dioxin response elements, after binding to the liganded AHR are sufficient to transactivate luciferase expression in a reporter gene system. The IL-2 gene can be induced by the AHR also in thymocytes in vivo after injection of 2,3,7, 8-tetrachlorodibenzo-p-dioxin, a potent ligand of the AHR. The AHR mediates the IL-2 induction as shown with AHR-deficient mice. However, in spleen cells in vitro costimulation via the TCR is necessary for optimal IL-2 gene induction. Thus, the IL-2 promoter region contains novel distal regulatory elements that can be addressed by the AHR to induce IL-2 and can cooperate with the proximal promoter in this.

ICAM-1-induced expression of proinflammatory cytokines in astrocytes: involvement of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase pathways

ICAM-1 is a transmembrane glycoprotein of the Ig superfamily involved in cell adhesion. ICAM-1 is aberrantly expressed by astrocytes in CNS pathologies such as multiple sclerosis, experimental allergic encephalomyelitis, and Alzheimer's disease, suggesting a possible role for ICAM-1 in these disorders. ICAM-1 has been shown to be important for leukocyte diapedesis through brain microvessels and subsequent binding to astrocytes. However, other functional roles for ICAM-1 expression on astrocytes have not been well elucidated. Therefore, we investigated the intracellular signals generated upon ICAM-1 engagement on astrocytes. ICAM-1 ligation by a mAb to rat ICAM-1 induced mRNA expression of proinflammatory cytokines such as IL-1alpha, IL-1beta, IL-6, and TNF-alpha. Examination of cytokine protein production revealed that ICAM-1 ligation results in IL-6 secretion by astrocytes, whereas IL-1beta and IL-1alpha protein is expressed intracellularly in astrocytes. The involvement of mitogen-activated protein kinases (MAPKs) in ICAM-1-mediated cytokine expression in astrocytes was tested, as the MAPK extracellular signal-regulated kinase (ERK) was previously shown to be activated upon ICAM-1 engagement. Our results indicate that ERK1/ERK2, as well as p38 MAPK, are activated upon ligation of ICAM-1. Studies using pharmacological inhibitors demonstrate that both p38 MAPK and ERK1/2 are involved in ICAM-1-induced IL-6 expression, whereas only ERK1/2 is important for IL-1alpha and IL-1beta expression. Our data support the role of ICAM-1 on astrocytes as an inflammatory mediator in the CNS and also uncover a novel signal transduction pathway through p38 MAPK upon ICAM-1 ligation.

An essential role for antibody in neutrophil and eosinophil recruitment to the cornea: B cell-deficient (microMT) mice fail to develop Th2-dependent, helminth-mediated keratitis

Invasion of the corneal stroma by neutrophils and eosinophils and subsequent degranulation disrupts corneal clarity and can result in permanent loss of vision. In the current study, we used a model of helminth-induced inflammation to demonstrate a novel role for Ab in mediating recruitment of these inflammatory cells to the central cornea. C57BL/6 and B cell-deficient (microMT) mice were immunized s. c. and injected intrastromally with Ags from the parasitic helminth Onchocerca volvulus (which causes river blindness). C57BL/6 mice developed pronounced corneal opacification, which was associated with an Ag-specific IL-5 response and peripheral eosinophilia, temporal recruitment of neutrophils and eosinophils from the limbal vessels to the peripheral cornea and subsequent migration to the central cornea. In contrast, the corneas of microMT mice failed to develop keratitis after intrastromal injection of parasite Ags unless Ags were injected with immune sera. Eosinophils were recruited from the limbal vessels to the peripheral cornea in microMT mice, but failed to migrate to the central cornea, whereas neutrophil recruitment was impaired at both stages. With the exception of IL-5, T cell responses and peripheral eosinophils were not significantly different between C57BL/6 and microMT mice. Taken together, these findings not only demonstrate that Ab is required for the development of keratitis, but also show that recruitment of neutrophils to the cornea is Ab-dependent, whereas eosinophil migration is only partially dependent upon Ab interactions.

Blocking antibodies induced by specific allergy vaccination prevent the activation of CD4+ T cells by inhibiting serum-IgE-facilitated allergen presentation

Allergen-specific CD4+ T lymphocytes are activated at extremely low allergen concentrations in vivo as a result of serum-facilitated allergen presentation (S-FAP). It is not clear at present if specific allergy vaccination (SAV) has an effect on this mechanism. Here we show that birch allergen-specific serum-IgE facilitates the presentation of Bet v 1, the major birch pollen allergen, to Bet v 1-specific CD4+ T lymphocytes by a factor of >100. This process is CD23 mediated, could be detected in sera from the majority of birch-allergic patients, and was clearly dose dependent. S-FAP of Bet v 1 was inhibited in patients undergoing long-term birch SAV, but not by sera from patients undergoing grass SAV, indicating that birch-specific Abs are involved. This resulted in decreased proliferation and IL-4, IL-5, IL-10, and IFN-gamma production of Bet v 1-specific T cells. The inhibition was already noted after 3-9 mo of SAV and could not be solely explained by increased serum levels of birch-specific IgG4. When IgG- and IgA/IgM-containing fractions of long-term SAV sera were used to inhibit S-FAP, only IgG-containing fractions were shown to inhibit S-FAP. These results indicate that blocking IgG Abs induced by SAV inhibits the occurrence of S-FAP at very low allergen concentrations, resulting in significantly higher allergen threshold levels to obtain T cell proliferation and cytokine production and thus allergen-induced late-phase responses.

Murine IgG1 complexes trigger immune effector functions predominantly via Fc gamma RIII (CD16)

Previously, we have demonstrated that phagocytosis of IgG1-coated particles by macrophages in vitro is impaired by deletion of Fc gamma RIII in mice, suggesting that IgG1 may interact preferentially with Fc gamma RIII. In the present study, the biologic relevance of this observation was addressed by triggering various effector functions of the immune system in Fc gamma RIII(-/-) mice, using panels of mAbs of different IgG subclasses. Both binding and phagocytosis of IgG1-coated sheep or human erythrocytes by Fc gamma RIII(-/-) macrophages in vitro were strongly impaired, indicating that the impaired ingestion of complexed IgG1 by Fc gamma RIII(-/-) macrophages is due to a defect in binding. An in vivo consequence of the defective phagocytosis was observed by resistance of Fc gamma RIII-deficient mice to experimental autoimmune hemolytic anemia, as shown by a lack of IgG1-mediated erythrophagocytosis in vivo by liver macrophages. Furthermore, trapping of soluble IgG1-containing immune complexes by follicular dendritic cells in mesenteric lymph nodes from Fc gamma RIII(-/-) mice was abolished. Whole blood from Fc gamma RIII(-/-) mice was unable to induce lysis of tumor cells in the presence of IgG1 antitumor Abs. Finally, IgG1 mAbs proved unable to mount a passive cutaneous anaphylaxis in Fc gamma RIII(-/-) mice. Together, these results demonstrate that IgG1 complexes, either in particulate or in soluble form, trigger in vitro and in vivo immune effector functions in mice predominantly via Fc gamma RIII.

Functional activity of antibodies at the bovine beta2-adrenoceptor

Antibodies that can activate beta2-adrenoceptors (beta2-AR) have the potential to mimic the anabolic effects of beta-agonist drugs, such as clenbuterol. In this study, antibodies were raised in rabbits against two peptide analogues of the human beta2-adrenoceptor (beta2-AR): One peptide corresponded to the complete second outer loop of the receptor (24 amino acids; H24T), and the second peptide was a truncated version of the first (13 amino acids; H13C). Following affinity purification, the antibodies were screened to detect interaction with beta2-AR in vitro. Membrane proteins from transformed Escherichia coli that express the beta2-AR were separated using SDS PAGE and transferred to nitrocellulose sheets. Immunoblotting revealed a single protein band (39,000 Da) that was recognized by the affinity-purified anti-H24T antibodies. However, the anti-H13C antibodies did not recognize any protein bands in immunoblots. In ligand binding studies, anti-H24T antibodies at a concentration of 50 nM, increased the affinity (KD) of the radiolabeled antagonist [125I]iodocyanopindolol for the bovine beta2-AR from 31.7 pM to 25.3 pM (P < .05) without changing the receptor number. Anti-H13C antibodies had no effect on ligand binding. In competitive ligand binding experiments, there was no effect of antibodies on the affinity of bovine beta2-AR for the agonist (-)-isoproterenol. However, functional activity of anti-H24T antibodies was demonstrated in an organ bath study. The presence of antibodies caused a leftward shift in the concentration-response curve for (-)-isoproterenol-induced relaxation of isolated bovine smooth muscle strips. Values for pD2 (-log EC50) were reduced in the presence of 10 nM antibody (8.62 +/- .11) compared to controls (8.30 +/- .08; P < .05). Anti-H13C antibodies had no effect on (-)-isoproterenol-induced smooth muscle relaxation. These studies have demonstrated recognition, interaction, and functional activity of site-directed antibodies at the beta2-AR. Further studies will determine whether antibodies that potentiate activity at the beta2-AR may be evoked by the active immunization of cattle with the peptide H24T, and if so, whether this will cause the repartitioning of nutrients in a manner analogous to conventional beta2-agonists and thus provide an alternative to the use of xenobiotic compounds.

Characterisation of the antibody response to the extracellular region of recombinant thyrotropin receptor

Autoantibodies to the human thyrotropin receptor (TSH-R) are pathogenic in a number of autoimmune thyroid diseases including Graves' disease. We have characterised polyclonal antisera to TSH-R for antibodies which may mimic those present in autoimmune thyroid disease. For immunisations, recombinant extracellular region of human TSH-R which does not interact with its ligand TSH was used. The induced antibodies react with the full length membrane receptor in transfected mammalian cells by flow cytometry showing the presence of antibody capable of recognising the native functional receptor. The properties of the generated antibodies have been compared after two injections or following a multiple immunisation protocol with the receptor in adjuvant. High titre antisera were readily generated after the short injection protocol and further immunisations did not lead to any change in antibody titers. Analysis of the epitopes recognised using synthetic peptides confirmed previous observations that the immunodominant determinants localise to the amino and the carboxyl terminal part of the extracellular region of the receptor. Antisera from both rabbits contain TSH blocking antibody as assessed by inhibition of TSH mediated cAMP stimulation. There was an increase in TSH binding inhibitory immunoglobulin (TBII) activity with multiple injections. Furthermore, the increase in TBII activity was not related to spreading of the antibody response to new determinants on TSH-R. Our results support previous observations on the difficulties in reproducing, by adjuvant immunisation with recombinant TSH-R preparations, the fine specificity of antibodies to TSH-R present in autoimmune disorders such as Graves' disease or primary myxoedema.

A novel approach to identify proteins associated with the inhibition of neurite growth

In the present study, a novel combination of techniques was used to identify the genes that may be involved in the lack of axonal regeneration in the mammalian adult central nervous system (CNS). The key features of this approach are: (1) a functional assay that can be affected by antibody perturbation; (2) increased specificity of the polyclonal antiserum by adsorption; (3) the expression cloning of the genes from a lambdagt11 library; (4) amplification of the insert cDNA by PCR; and (5) the direct cycle sequencing of PCR products. In this culture assay system, neurons were plated directly on sections of the rat CNS. This assay system could be used to demonstrate the lack of neuronal attachment to or neurite extension over myelinated regions of the CNS (white matter). This prohibitive nature of the CNS sections could be masked by a rabbit polyclonal antiserum directed against rat CNS white matter. This data indicates that the anti-white matter antiserum recognizes and neutralizes inhibitory molecules on the surface of the sections. Making the assumption that the prohibitive antigen is associated with the cell membrane, the antiserum was adsorbed against a soluble protein fraction of the adult rat brain. This adsorption significantly increased the specificity of the antiserum as demonstrated by immunoblot methods. The adsorbed antiserum was then used to screen the cDNA library of the adult rat brain. The present report describes this novel combination of techniques allowing one to go from a functional tissue culture assay system to defining the molecular basis for the cellular interactions.

Lack of effect of Miller Fisher sera/plasmas on transmitter release from PC12 cells

IgG antibodies to GQ1b ganglioside are found in > 90% of patients with the Miller Fisher Syndrome (MFS). MFS sera or IgG preparations have marked effects on neurotransmitter release at the neuromuscular junction, but their mode(s) of action remain unclear. To establish a cell-based system for investigating the mechanism of action of MFS serum preparations, we looked at neurotransmitter release from three cell lines. We failed to demonstrate substantial 14C-acetylcholine release from two motor-neuronal cell lines, VSC4.1 and NSC19, and therefore studied 3H-noradrenaline release from NGF-differentiated PC12 cells, a neural-crest derived catecholaminergic cell line. K(+)-induced release was inhibited by botulinum toxin and basal release was enhanced by alpha-latrotoxin, resembling that at the neuromuscular junction, although K(+)-induced release was dependent on L-type rather than P/Q-type calcium channels. The cells expressed polysialylated gangliosides on the cell surface. Incubation in heat-inactivated or untreated MFS preparations did not, however, affect basal or K(+)-induced release. Thus the PC12 cells do not appear to be sensitive to the effects of serum antibodies from MFS patients.

Specificity and role of anti-Trypanosoma cruzi clearance antibodies

Two strains of Trypanosoma cruzi (Y and CL) were used to study the specificity and role of anti-T. cruzi clearance antibodies. Clearance antibodies were only induced after immunization with living blood-stream trypomastigotes (Btrys) but not with dead parasites. Btrys of either strain were readily cleared from the circulation after passive immunization with anti-Y or anti-CL serum provided that the homologous strain was used. CL or Y Btrys sensitized in vitro with the homologous or heterologous antiserum and transferred to normal mice were cleared from the circulation only when the homologous antiserum was used. Clearance antibodies were removed from serum by absorption with the homologous but not with the heterologous strain. Clearance antibodies were removed from serum by absorption with living Btrys but not with fixed parasites. These results suggest that: a) the parasite epitopes involved in the clearance are peculiar to each strain, b) the clearance antibodies are specific to these epitopes, and c) a proper conformation of the parasite antigens is required for the induction and effector activity of the clearance antibodies.

Characterization of an inhibitory seric factor from tuberculosis anergic patients that acts on non-adherent PPD reactive cells

Non-adherent cells from PPD+ tuberculosis patients (TBP PPD+) and from healthy individuals treated with whole tuberculosis anergic immune sera or with its protein A-Sepharose IgG fraction, or with sera fraction separated by PPD-Sepharose chromatography, were submitted to immunofluorescence assays. Anti-human IgG or IgM FITC-conjugate were used to reveal the assays, and results were expressed by a fluorescence percentage or fluorescence index. The presence of IgG over the surface of PPD+ non-adherent cells was detected. High fluorescence percentages were observed only in those PPD+ cells treated with whole anergic serum or with its IgG fraction. Positive fluorescence index values were obtained only in those PPD+ cells treated with anergic serum, meanwhile fluorescence index was always negative when non-bound fractions from PPD-Sepharose were used. Results suggest that non-adherent population are the cell targets for the serum inhibitory factor, which previously has been detected to inhibit antigen response in PPD reactive cells and, point out the specific behavior of this factor, since it was eliminate by PPD-Sepharose chromatography. The IgG nature of the factor was demonstrated by SDS-PAGE and immunoelectrophoresis.

Immunization of monkeys with recombinant complimentary deoxyribonucleic acid expressed zona pellucida proteins

OBJECTIVE

To evaluate the effects of immunization with zona pellucida (ZP) proteins produced by recombinant complementary DNA (cDNA) technology for the elicitation and antibodies that inhibit sperm binding without altering ovarian function in the nonhuman primate.

DESIGN

Controlled nonhuman primate study.

SETTING

Controlled environment with individual housing of monkeys in facility approved by National Institutes of Health (NIH) guidelines.

PARTICIPANTS

Monkeys housed and treated according to NIH regulations.

INTERVENTIONS

Monkeys immunized and boosted at regular intervals with ZP proteins produced using recombinant cDNA techniques.

MAIN OUTCOME MEASURE

Urinary estrogen, P, serum antibody levels, sperm-ZP binding, and ovarian morphology.

RESULTS

Monkeys immunized with a recombinant rabbit 75-kd ZP protein expressed from a partial cDNA in the pEX bacteria expression system produce antibodies that interfere with ovarian follicular development and ovarian cyclicity. On the contrary, monkeys immunized with a recombinant rabbit 55-kd ZP protein develop antibodies that inhibit homologous sperm binding but do not affect ovarian follicular development or subsequent ovarian hormonal cyclicity.

CONCLUSION

Monkey antibodies to the rabbit 75-kd ZP recombinant protein can be generated that inhibit ovarian cyclicity as desired for animal sterilization vaccines. Antibodies to the 55-kd ZP recombinant protein inhibit homologous monkey sperm binding to the ZP without altering ovarian endocrine function or morphology as is desired for human immunocontraception.

Sheep small intestinal mast cells/globule leucocytes: ability to divide

The number of mucosal mast cells/globule leukocytes (MMC/GLs) increase in the intestinal mucosa in response to nematode parasite infections but it is not known if this accumulation is due to in situ cell division, derivation from elsewhere or some combination of both. To determine if MMC/GLs can divide, cells were obtained from immunized Romney sheep and cultured in vitro in RPMI 1640. For cultures supplemented with 10, 20 or 30% foetal lamb serum (FLS) or foetal calf serum (FCS) and without concanavalin A (Con A), cell division had ceased by day 2, but with Con A (3 micrograms ml-1) cell division continued to day 9. Better growth of cells was obtained with the higher concentrations of serum. However the use of 30% or 50% autologous serum with Con A lead to cell death but 10% serum permitted limited growth. The detrimental effect of autologous serum could be overcome by increasing the Con A concentration. It was established that an alpha-macroglobulin present in autologous serum can bind Con A. This macroglobulin appears to have a higher avidity for Con A than does the receptor(s) on the surface of MMC/GLs. Our data seem to indicate that a direct interaction of Con A with the cell surface or a receptor(s) is responsible for MMC/GLs division.

Adrenal and circulating renin-angiotensin system in stroke-prone hypertensive rats

The plasma and adrenal renin-angiotensin system in stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto (WKY) rats were examined in animals at 5, 11, 18, and 25 weeks of age. Plasma active renin was significantly increased in 18- and 25-week-old SHRSP with impaired renal function, whereas there was no difference in the plasma prorenin level or renal renin content between the two strains at all ages examined. Thus, the rate of activation of prorenin seems to be enhanced in the kidney of SHRSP with malignant hypertension. Adrenal renin contents were severalfold higher in SHRSP than WKY rats at all ages. However, adrenal angiotensin peptides were not increased in SHRSP aged 5 and 11 weeks. In 18-week-old SHRSP, adrenal angiotensin II (Ang II) and III (Ang III) levels were fourfold and 1.8-fold higher, respectively, than in WKY rats, accompanied by 1.5-fold higher plasma aldosterone. Increased adrenal angiotensin and plasma aldosterone were also found in 25-week-old SHRSP. Zonal distribution studies indicated that the elevated Ang II and III in SHRSP were derived mainly from the capsular tissue (the zona glomerulosa). To examine the contribution of circulating angiotensin to the adrenal angiotensin content, effects of bilateral nephrectomy on adrenal angiotensin and renin were examined in 18-week-old rats. At 24 hours after nephrectomy, plasma angiotensin, prorenin, and active renin were decreased to almost negligible concentrations. Conversely, in both adrenal capsular and decapsular tissues of SHRSP and WKY rats, neither angiotensin nor renin was significantly decreased after nephrectomy. These results suggest that the increase in adrenal capsular Ang II contents in SHRSP may be partly due to an enhanced local production of Ang II.

Mechanism of action of cytotoxic antibodies to adipocytes on adipose tissue, liver and food intake in the rat

The aim of this study was to characterize in greater detail the effects of anti-(rat adipocyte plasma membrane) antisera (A/S 83 and A/S 164) that had previously been shown to cause large reductions in total body fat. Both antisera produced lymphocytic infiltration of adipose tissue and reduction of adipocyte numbers seven days after treatment as well as a reduction in food intake and body weight on the first day of treatment. In addition A/S 164 produced a sedative effect for 2-4 h after treatment and induced gross abnormalities of the liver after seven days. Antibody-mediated complement activation was shown to be a critical requirement for all of these effects since animals treated with cobra venom factor (CVF) to deplete serum complement levels showed none of the described effects. Further evidence in support of a role for complement was the large decrease in serum complement levels 12 h after antiserum treatment. The effects of A/S 164 on liver morphology could be successfully dissociated from those on adipose tissue by adsorption of the antiserum with liver membranes. The adsorbed antiserum, which retained in vitro reactivity with adipose tissue but not with liver, induced a significant reduction in adipose tissue mass in vivo whilst the effect on liver morphology was almost completely abolished. Serum free fatty acid and triglyceride levels increased 6-24 h after treatment but then returned to normal, suggesting a very transient release of adipose tissue triglycerides. These results indicate that complement activation is a common pathway for all of the effects produced.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunosuppressive effect of paracoccidioidomycosis sera on the proliferative response of normal mononuclear cells. Identification of a Paracoccidioides brasiliensis 34-kDa polypeptide in circulating immune complexes

In this paper we relate that sera from paracoccidioidomycosis patients inhibited the mitogen-induced proliferative responses of normal mononuclear cells. Treatment of these sera with 2.5% polyethyleneglycol (PEG), a method classically used to precipitate immune complexes, significantly reduced their inhibitory activity. Immunoblot analysis of the PEG precipitates identified a 34-kDa polypeptide, recognized by rabbit anti-P. brasiliensis IgG. Patient mononuclear cells showed partial restoration of their proliferative capacity after 24 h culture in medium alone, which suggests release of membrane-bound molecules in the culture medium. These findings indicate that circulating P. brasiliensis antigens, complexed or not with antibodies, may play a negative immunoregulatory effect in the mitogen-induced proliferative responses of paracoccidioidomycosis patients.

Common epitopes of mammalian amelogenins at the C-terminus and possible functional roles of the corresponding domain in enamel mineralization

The present studies were undertaken to investigate the presence of common epitopes of mammalian amelogenins at the C-terminus and the possible functional importance of the conserved C-terminal domain in enamel mineralization during mammalian amelogenesis. Enamel proteins, including the intact amelogenins and their degraded polypeptides, were isolated from the secretory enamel of pig, cow, rat, and rabbit incisors. Rabbit and rat antipeptide sera, as well as rat anti-25 kD and 20 kD pig amelogenin sera, were used to identify the amelogenins among the isolated matrix proteins of each of the animal species. The antipeptide sera were developed previously (Aoba et al. [19]) using as immunogens the two synthetic peptides, C13 and C25, which correspond to the last 12 (plus Cys for KLH-conjugation) and 25 amino acid residues of pig intact amelogenin, respectively. Reactivity of the enamel proteins with each antiserum was examined by Western blot analysis. The results of immunoblotting showed that a few enamel matrix proteins in each of the mammalian species were recognized by the anti-C13 serum, specifically, pig amelogenin at 25 kD (and trace components at 27, 22, and 18 kD), cow amelogenin at 28 kD (trace components at 26, 22, 19, and 14 kD), rat amelogenins at 28 and 26 kD (and a trace component at 20 kD), and rabbit amelogenins at 24 and 21 kD (and a trace at 13 kD). The anti-C25 serum reacted additionally with pig amelogenin at 23 kD, cow amelogenin at 27 kD (a major matrix constituent), and rabbit protein at 19 kD.(ABSTRACT TRUNCATED AT 250 WORDS)

Dependency on the brain function of arginine vasopressin system of the development to and recovery from analgesic tolerance to morphine

Concomitant intracerebroventricular (i.c.v.) injection of anti-arginine vasopressin (AVP) antiserum dose-dependently suppressed the development of analgesic tolerance to daily morphine, 10 mg/kg, s.c., in mice. This suppressive effect of the antiserum was reduced by incubating the antiserum with AVP in vitro, before i.c.v. injection, suggesting that the antiserum inactivates brain AVP to result in the suppression of the development of tolerance in vivo. Similar to the antiserum, both AVP V1 and V2 antagonists given i.c.v., 10 ng and 20 ng/mouse, respectively, suppressed the development of morphine tolerance. Meanwhile, the administration of antiserum dose-dependently recovered morphine analgesia in morphine-tolerant mice and a complete recovery of analgesia was observed at the highest dose of antiserum following the second injection, and the effect of antiserum was maintained for 3 days after its withdrawal. Likewise, 10-100 ng/mouse of AVP V1 receptor antagonist given i.c.v. recovered morphine analgesia partially but significantly in a dose-dependent manner; however, AVP V2 receptor antagonist at the same doses partially recovered analgesic effect but the effect was neither significant nor dose-dependent. These findings suggest that the tolerance developed to morphine can be reversible when disturbing the function of brain AVP, but in addition to the different mechanisms of antiserum, V1 and V2 receptor antagonists, the V1 receptor-mediated mechanism may be more closely concerned in this phenomenon.

Sertoli cell plasma membrane polypeptides involved in spermatogenic cell-Sertoli cell adhesion

This study concerns Sertoli cell-spermatogenic cell adhesive interactions in the seminiferous tubule. Sertoli cell surface polypeptides involved in germ cell-Sertoli cell adhesion were identified by serological inhibition of an in vitro Sertoli-germ cell adhesion assay. This assay was modified from a previously reported adhesion assay, and employs a scanning laser cytometer for quantification of adherent cells. Reactivity of the polyclonal antiserum raised against rat Sertoli cells was also assessed via immunofluorescent microscopy. The addition of antiserum to the adhesion assay resulted in a 42% to 66% inhibition of cell-cell adhesion. Moreover, preincubation of antiserum with Sertoli cell monolayers resulted in a significant reduction of spermatogenic cell binding. Conversely, preincubation of antiserum with germ cells resulted in no reduction. Western blot analysis of the antiserum against purified Sertoli cell membranes indicated reactivity with four polypeptides. The data suggest that one or more of these polypeptides are directly involved in the adhesion of germ cells to Sertoli cell monolayers in vitro.

The influence of different sera on the in vitro immobilisation of Percoll purified Treponema pallidum, Nichols strain

OBJECTIVES

Investigation of sera, especially rabbit serum, in preventing in vitro immobilisation of Percoll purified T. pallidum.

MATERIALS AND METHODS

The immobilisation of Percoll purified T. pallidum (Nichols) was studied after pre-incubations with basal reduced medium (BRM), heat-inactivated serum of seven different species of animals, heat-inactivated normal human serum (NHS) and rabbit sera containing a different level of antitreponemal antibodies. Also increasing percentages of heat-inactivated normal rabbit serum (NRS) were studied.

RESULTS

The rapid immobilisation of purified treponemes by NHS is delayed by pre-incubation with NRS in a dose-dependent manner. The treponemes from 5-day infections were immobilised significantly more slowly than treponemes from 7- and 8-day infections. Compared with NRS, pre-incubations with a high-titred, low-titred and "autologous" serum resulted in significantly more rapid immobilisation of the treponemes. With most other animal sera resistance to immobilisation was slight compared with that produced by NRS. Immunofluorescent studies revealed that the treponemes were covered with a layer of the human third complement factor (C3b), within an hour of incubation. With two sequential pre-incubations, a delay of the immobilisation was only noted in those test mixtures in which NRS had been present in both preincubations.

CONCLUSION

Rabbit serum delays the rapid in vitro immobilisation of Percoll purified treponemes by normal human serum. There was no evidence that this was caused by preventing access of antibodies (in vivo as well as in vitro) to, or preventing the activation of complement on, the treponemal surface. The evidence points to a mechanism in the fluid phase, suggesting participation of a third factor in the immobilisation process, for instance an enzyme, which can be partially inhibited by rabbit serum component(s).

Cytokine regulation of neuronal survival

Interleukin-1 is a cytokine involved in the immune response to infection and inflammation as well as a growth promotor for several cell types. Interleukin-1-like immunoreactive material has been found in the nervous system. We now show that antisera, which blocked the T-cell proliferative effects of interleukin-1 alpha, decreased neuronal cell counts (to 40% of control) in dissociated spinal cord cultures derived from fetal mice. This neuronal loss was prevented by addition of interleukin-1 alpha, and to a lesser extent by interleukin-1 beta. Exogenous interleukin-1 alpha increased the survival of neurons when added to cultures in which the electrical activity was blocked with tetrodotoxin, whereas no such cytokine-related increase in neuronal survival was observed in electrically active cultures. The antiserum-induced death could also be prevented by cotreatment of the cultures with 0.1 nM vasoactive intestinal peptide, a substance that induces the secretion of neuronal trophic factors from nonneuronal spinal cord cells and thereby increases neuronal survival in electrically inactive cultures. These studies indicate that the cytokine interleukin-1, or an immunologically cross-reactive protein, can increase neuronal survival.

Growth state and cell cycle dependent phosphorylation of DNA topoisomerase II in Swiss 3T3 cells

We have investigated the amount of DNA topoisomerase II and phosphorylation of the enzyme in Swiss 3T3 cells during the transition from cell quiescence to proliferation. A relatively high level of phosphorylation was observed with proliferating cells while no or a very low level of phosphorylation was observed with quiescent cells. Phosphoamino acid analysis of the phosphorylated topoisomerase II revealed that the phosphorylated aminoacyl residue was serine. When quiescent cells were stimulated to grow by the addition of serum, DNA synthesis began to increase at 9 h after serum addition, reaching a maximum at 15 h and then declining. The amount of topoisomerase II began to increase at 6 h and reached a maximum at 22-27 h, corresponding to the G2 phase. The phosphorylation of topoisomerase II measured by pulse-labeling gradually increased from 6 to 18 h and reached a maximum at 22 h when the amount of the enzyme was maximum. The level of phosphorylation measured by continuous-labeling increased gradually up to 12 h and markedly up to 28 h, and then declined. The increase in the rate of phosphorylation in the G2 phase was affected by inhibiting DNA synthesis, but the increase in the amount of the enzyme was not. Thus, it was suggested that the regulation of phosphorylation of topoisomerase II differs from that of the amount of the enzyme.

Two generalized transducing phages in Vibrio parahaemolyticus and Vibrio alginolyticus

Two bacteriophages named phi VP253 and phi VP143 isolated after ultraviolet induction from lysogenic strains of Vibrio parahaemolyticus have been shown to be generalized transducing phages. So far, seven different auxotrophic markers of a V. parahaemolyticus strain could be transduced at the frequencies ranging from 2.2 x 10(-7) to 7.5 x 10(-5) per infected cell at the m.o.i. of approximately 1.0. The phage phi VP143, but not phi VP253, lysed 20 of the 28 strains of V. alginolyticus and the occurrence of generalized transduction by this phage in this Vibrio species has been confirmed. Molecular size of the genomes of both phages were estimated to be approximately 48 kb as judged from electrophoretic mobilities of the DNAs digested with HindIII endonuclease. The results and similarity of the two phages in morphology and other properties suggest very close relatedness of the phages.

Attenuation of the suckling-induced prolactin release and the high afternoon oscillations of plasma prolactin secretion of lactating rats by antiserum to vasopressin

To investigate the role of vasopressin in prolactin (PRL) release during lactation, vasopressin antiserum (VP-Ab) was administered to lactating rats, giving it intravenously 15 min before permitting their previously isolated pups to suckle or to continuously suckled rats. The suckling-induced rise in plasma PRL levels was significantly less in VP-Ab-treated mothers than in rats receiving a similar amount of normal rabbit serum (NRS). The inhibitory effect of VP-Ab could not be detected on the next day. Angiotensin II antiserum (AII-Ab) had no effect on plasma PRL response induced by suckling. VP-Ab given to continuously suckled rats reduced the high amplitude oscillation of PRL concentration observed in NRS-injected rats. A transient increase of water intake was detected on the day of VP-Ab treatment only, which provides direct evidence for at least partial neutralization of vasopressin in the circulation. These findings suggest that vasopressin released from the neural lobe of the pituitary gland is essential for the normal PRL secretory response induced by suckling and the episodic pattern of PRL release in continuously suckled mother rats. Furthermore, these results support the assumption that disturbance in the regulation of water and electrolyte balance at the level of the neuro-intermediate lobe of the pituitary gland may alter PRL secretion during lactation.

Effect of exogenous or endogenous gastric inhibitory polypeptide (GIP) on plasma triglyceride responses in rats

We examined the effects of exogenous and endogenous GIP on plasma triglyceride levels in rats, pretreated with a fat-enriched diet, during intraduodenal infusion of a lipid test meal (Lipomul, 8 ml/h). Following the fat load the plasma triglyceride levels increased nearly linearly from a fasting value of 0.621 +/- 0.031 mmol/l to 3.32 +/- 0.403 mmol/l at 150 min. Simultaneously, the plasma GIP levels rose from 47.1 +/- 5.1 at fasting to a peak value of 268.4 +/- 32.2 pmol/l at 120 min. When porcine GIP was infused intravenously during the fat load, the plasma triglyceride increments were significantly smaller (control 1.64 +/- 0.264 mmol/l versus 0.949 +/- 0.114 mmol/l during GIP infusion at 60 min; p less than 0.002). GIP infusion in the absence of the fat load did not change fasting triglyceride levels. The effect of endogenous GIP was investigated by neutralization of GIP by injection of GIP antiserum (0.3 ml). Rats pretreated with the antiserum exhibited a significantly greater triglyceride increment late in the time course of the fat load. These data demonstrate that exogenous and endogenous GIP are able to lower the plasma triglyceride response to a fat load. Both, inhibition of fat absorption or stimulation of triglyceride uptake by peripheral tissues may be responsible for the GIP effects. The gut peptide GIP seems to represent an important hormonal regulator of postprandial triglyceride response.

Mediation of follicle-stimulating hormone action on follicular deoxyribonucleic acid synthesis by epidermal growth factor

FSH stimulates DNA synthesis by hamster preantral follicles both in vivo and in vitro, and the in vitro mitogenic effect of FSH is effectively reproduced by epidermal growth factor (EGF). To determine whether follicular EGF is the intracellular transducer of FSH action on hamster preantral follicles, intact follicles at stages 1 to 7 (stages 1-4 = preantral follicles 1-4 layers of granulosa cells, respectively, and no theca; stages 5-6 = 5-6 and 7-8 layers granulosa cells, respectively, and developing theca; and stage 7 = follicles with incipient antrum) were cultured for 24 h in a serum-free culture medium in the absence or presence of 100 ng FSH, 50 ng EGF, 50 ng transforming growth factor-alpha (TGF alpha), or 1 mumol 8-Br-cAMP and challenged with 50 microliters polyclonal antimurine EGF antiserum; the rate of DNA synthesis was determined by [3H]thymidine incorporation. FSH, EGF, and TGF alpha significantly (P less than 0.05) stimulated follicular DNA synthesis; TGF alpha per se was less effective than either FSH or EGF. However, both FSH- and EGF-induced DNA synthesis was drastically attenuated by EGF antiserum; TGF alpha effect remained undisturbed. Interestingly antibody inhibition of FSH-induced DNA synthesis was totally reversed by coexposure to TGF alpha. Follicular DNA synthesis for most stages was stimulated by Br-cAMP, but the effect was significantly (P less than 0.05) inhibited by EGF antibody. Moreover, follicles at different stages responded to EGF with different latency. These results strongly suggest that FSH-induced follicular DNA synthesis in the hamster is mediated by follicular EGF and the pathway of events is FSH action----cAMP production----EGF synthesis----cell proliferation.

Effect of antiserum to rat growth hormone (GH)-releasing factor on physiological GH secretion in the female rat

To further study the physiological role of GH-releasing factor (GRF), we examined the effect of antiserum to rat hypothalamic GRF on spontaneous GH secretion in the normal female rat. Two groups of six conscious female rats were passively immunized with either nonimmune rabbit serum (NRS) or antirat GRF serum via a chronic indwelling atrial catheter. The secretory profiles of GH were observed by collecting blood samples at 15-min intervals for 1 h before and 4 h after administration. The NRS-treated rats showed a characteristic female pattern of spontaneous GH secretion. GH pulses were of low amplitude (mean +/- SEM, 26.8 +/- 2.4 ng/ml) and occurred irregularly at a frequency of 4.2 +/- 0.2/5 h, while interpeak through levels of GH were relatively high, with nadir values of 8.6 +/- 0.7 ng/ml. Synthetic rat GRF, given iv at a dose of 1 microgram/kg BW after the last blood sampling, stimulated GH release to a peak level of 153 +/- 37 ng/ml in the control rats. Administration of GRF antiserum caused a profound suppression of both pulse and trough components of GH secretion. This effect occurred rapidly, within 15 min after injection of antiserum, and GH secretion decreased uniformly to very low levels (3.4 +/- 0.1 ng/ml), with little or no fluctuation throughout the observation period. GRF antiserum also abolished the synthetic rat GRF-induced GH release, indicating sufficient potency of immunoneutralization. These results demonstrate that both GH pulses and troughs are dependent upon hypothalamic GRF in normal female rats, thereby substantiating earlier observations in male rats which demonstrated the physiological role of GRF in GH secretion.

Intracerebroventricular atrial natriuretic factor (ANF) antiserum inhibits volume-induced ANF in sheep: evidence for the brain's regulation of ANF secretion

Plasma volume expansion stimulates cardiac secretion of atrial natriuretic factor (ANF) and also increases the ANF concentration in cerebrospinal fluid. In order to determine whether brain ANF is involved in the compensatory response to hypervolemia or the regulation of cardiac secretion of ANF, we have studied the integrated hemodynamic, renal, and hormonal response to acute volume expansion (15 ml/kg Dextran over 30 min) in five sheep given nonimmune serum (control) and ANF antiserum by intracerebroventricular (icv) injections on separate days. Dextran loading caused similar decreases in hematocrit and increases in central venous and mean arterial pressures on both study days. Heart rate was higher after antiserum injections (P less than 0.05). Dextran loading increased plasma ANF on the control (20 pmol/liter maximal mean increment above baseline) but not on the antiserum day (P less than 0.01). The diuresis (P less than 0.01) and natriuresis (P less than 0.05) observed on the control day was inhibited by icv antiserum. Plasma aldosterone and cortisol levels showed similar falls in response to the dextran load on both days. These experiments show that icv ANF antiserum inhibits both the increase in cardiac secretion of ANF and the renal response to plasma volume expansion without affecting hemodynamic status. These data support the hypothesis that the brain ANF system is important in the systemic responses to volume loading.

Nerve growth factor modulates the activation of the hypothalamo-pituitary-adrenocortical axis during the stress response

In the present study, we have investigated the functional relationship between the nerve growth factor protein (NGF) and the hypothalamus-pituitary-adrenocortical axis (HPAA). We have found that while iv injected NGF is able to stimulate the HPAA activity in rats, NGF is not able to stimulate the axis after a block of the hypothalamus produced by chlorpromazine-morphine-Nembutal treatment. Also, the stress activation of the HPAA is significantly reduced by pretreatment of the rats with anti-NGF immunoglobulin G. These results suggest that the stimulatory action of NGF on HPAA activity requires the release of ACTH secretagogues from the hypothalamus and that NGF may modulate the HPAA response to stress stimuli.

Cholinergic modulation of growth hormone secretion induced by galanin in rats

The effects of cholinergic modulation by hexamethonium (HEX), tetraethylammonium (TEA), pirenzepine (PIR) and neostigmine on growth hormone (GH) secretion induced by galanin (GAL) were investigated in awake, freely moving male rats. Intracerebroventricular (i.c.v.) injection of GAL (0.6 nmol) caused a marked increase in plasma GH levels. Pretreatment with HEX (3 or 15 mg/kg BW), TEA (15 mg/kg BW) or PIR (0.5 mg/kg BW) significantly reduced the GAL-induced GH secretion. Pretreatment of animals with neostigmine (0.05 mg/kg BW) or with a specific antisomatostatin antiserum (10 microliters of 1:10 diluted with saline, i.c.v.) reversed the inhibition of GAL-induced GH secretion by HEX. These findings suggest that both nicotinic and muscarinic cholinergic mechanisms interact with the galanin-induced GH secretion by modulating hypothalamic somatostatin release.

Antiserum against tumor necrosis factor-alpha and a protease inhibitor reduce immune glomerular injury

Previous studies in this laboratory have documented tumor necrosis factor alpha (TNF) release by macrophage laden glomeruli in the accelerated autologous form of nephrotoxic serum nephritis (AA-NTSN). We now report that the administration of anti-TNF antiserum to rats with the AA-NTSN reduces albuminuria in a dose related manner (day 8 postinduction) and limits glomerular necrosis (P less than 0.05) without affecting the endogenous creatinine clearance (CCr). Protease inhibitors block cytolytic activity of TNF in vitro and reduce glomerular necrosis in experimental nephritis in vivo. The combined administration of anti-TNF antiserum and an amidine-type protease inhibitor (BABIM) to rats with the AA-NTSN caused a greater diminution of albuminuria and histopathology than observed in rats treated with either agent alone, and also prevented the fall in CCr otherwise observed in this model system. Since, in our studies, BABIM did not inhibit cytolytic TNF activity in vitro, we conclude that the effects of combined administration of these two agents are mediated by independent mechanisms. Our results highlight the pathogenic significance of local TNF release in immune renal disease accompanied by prominent glomerular macrophage accumulation.

Endothelial cell damage by Walker carcinosarcoma cells is dependent on vitronectin receptor-mediated tumor cell adhesion

The transport of cancer cells from blood vessels to extravascular tissue is a critical step in metastasis, where endothelial cells and the vascular basement membrane act as barriers to cell traffic. Because endothelial injury can facilitate the metastasis of intravascular cancer cells in vivo, the authors have studied in vitro the free-radical-mediated endothelial damage caused by the rat Walker 256 carcinosarcoma (W256) cell after stimulation with 10(-6) mol/l (molar) phorbol ester. Here the authors have examined the hypothesis that W256 cell-mediated endothelial injury is dependent on adhesion between the effector and target cells. Attachment of phorbol 12-myristate, 13-acetate (PMA)-stimulated W256 cells to endothelial monolayers was increased 1.8 +/- 0.1-fold and damage (3H-2-deoxyglucose release from labeled endothelium) 1.4 +/- 0.1-fold after 4-hour pretreatment of the endothelium with 10 ng/ml recombinant human interleukin-1 alpha (rIL-1 alpha). Under various assay conditions, the release of 3H-2-deoxyglucose correlated directly with tumor cell adhesion (r = 0.98, P less than 0.005). In the presence of a polyclonal anti-vitronectin receptor antiserum, adhesion of stimulated W256 cells to rIL-1 alpha-treated monolayers was inhibited by 39% +/- 2%, and 3H-2-deoxyglucose release was inhibited by 53% +/- 13%. Immunoblot analysis and immunofluorescence flow cytometry demonstrated that the endothelial cells but not the W256 cells expressed vitronectin receptor (VnR) on their cell surface. The surface expression of VnR by endothelial cells was increased 1.9 +/- 0.1-fold after 4 hours' incubation with rIL-1 alpha. The authors conclude that W256 cell-mediated endothelial damage is dependent on cell adhesion, which, in turn, is partly regulated by the expression of VnR on the endothelial cell surface.

Role of endogenous atrial natriuretic peptide in regulating sodium excretion in spontaneously hypertensive rats. Effects of neutral endopeptidase inhibition

To explore whether pathophysiological plasma levels of atrial natriuretic peptide (ANP) actually involve sodium excretion in spontaneously hypertensive rats (SHR), we examined the in vivo and ex vivo effects of ANP and an endopeptidase inhibitor, thiorphan, on urinary sodium excretion and the elimination rate of ANP. We found the following: 1) The basal plasma ANP level was higher in 16-week-old SHR than in Wistar-Kyoto (WKY) rats (109 +/- 10 [SEM] versus 63 +/- 4 pg/ml, p less than 0.001). Thiorphan (30 mg/kg i.v.) significantly increased plasma ANP by 60% in both SHR and WKY rats. However, increases in urinary sodium excretion (+290% versus +130%, p less than 0.05) and cyclic GMP (+160% versus +60%, p less than 0.05) were greater in SHR than in WKY rats. Urinary excretion of ANP was markedly increased by thiorphan, and its increase was greater in SHR than in WKY rats. 2) The thiorphan-induced natriuresis was substantially attenuated by antiserum for ANP but not by a bradykinin receptor antagonist. 3) Isolated SHR kidneys excreted 50% less sodium than WKY rat kidneys at perfusion pressures of 100 and 160 mm Hg (p less than 0.05). Urinary sodium excretion was increased at the perfusate ANP level of 100 pg/ml, a concentration similar to the SHR plasma ANP (+70% at 160 mm Hg). 4) After bolus administration of ANP to the isolated kidney, the ANP concentration of the recirculating perfusate decreased rapidly in a log-linear fashion.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of endothelin effects on blood pressure and hematocrit by atrial natriuretic peptide

Infusion of endothelin has been observed to increase hematocrit, and the peptide also stimulates release of atrial natriuretic peptide (ANP) both in vitro and in vivo. We studied the relation of these two actions of endothelin in anesthetized, bilaterally nephrectomized Sprague-Dawley rats. Infusion of endothelin (25 ng/kg/min) for 45 minutes produced a modest increase in blood pressure of 12% from a baseline of 99 +/- 5 mm Hg and an increase in hematocrit of 8.0 +/- 0.6%, reflecting a reduction in plasma volume of 13.1 +/- 0.9%. These changes each exceeded greatly those observed after 45 minutes of vehicle infusion. Plasma protein concentration, however, increased only by 4.2 +/- 0.6%, suggesting protein extravasation, which was confirmed by finding an endothelin-dependent increase in the accumulation of Evans blue dye in heart, skeletal muscle, and intestine, but not liver, lung, brain, or testis. Endothelin infusion increased plasma immunoreactive ANP concentration from 196 +/- 50 to 722 +/- 203 pg/ml (p less than 0.02), and a close correlation existed between the increase in plasma immunoreactive ANP and immunoreactive endothelin concentrations as a result of the infusion (r = 0.84, p less than 0.01). Pretreatment of rats with rabbit anti-rat ANP antiserum did not affect baseline variables but led to an exaggerated increase in blood pressure (25.3 +/- 2.9%, p less than 0.002 versus endothelin alone). No change in hematocrit occurred. Thus, the increase in plasma immunoreactive ANP concentration resulting from endothelin infusion mediates the increase in hematocrit through an increase in vascular permeability to whole plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

An Epstein-Barr virus-negative Burkitt lymphoma cell line (sfRamos) secretes a prolactin-like protein during continuous growth in serum-free medium

Pituitary human PRL (hPRL) antiserum inhibits growth of B-lymphoblastoid cells in vitro, but the mechanism of inhibition is unclear. In this study the mechanism of inhibition of human B-cell growth by anti-hPRL was explored with an Epstein-Barr virus nuclear antigen (EBNA)-negative Burkitt lymphoma cell line (sfRamos) that proliferates continuously in serum-free medium with human transferrin as the only protein supplement. The data show that antiserum immunoglobulin fraction G (IgG) to pituitary hPRL, but not nonimmune serum IgG, completely inhibited the growth of sfRamos cells. In addition, anti-hPRL IgG identified a single band (29 kDa) in sfRamos spent medium, but not in fresh serum-free medium or in human transferrin, as demonstrated by sodium dodecyl sulfate-reducing polyacrylamide gel electrophoresis and Western immunoblot analysis. Polyacrylamide gel electrophoresis and Western analysis of a mixture containing sfRamos spent medium and excess pituitary hPRL established that the sfRamos 29-kDa PRL-like protein (PLP29) and pituitary hPRL (23 kDa) were electrophoretically distinct. Finally, sfRamos spent medium, but not fresh serum-free medium, was mitogenic for sfRamos and Nb2, a PRL-sensitive node rat lymphoma cell line. These findings demonstrate that PLP29 is biologically and immunologically like pituitary hPRL, but is electrophoretically different from this hormone. We suggest that PLP29 is secreted as an autocrine growth factor by sfRamos Burkitt lymphoma cells during continuous serum-free growth.

Differential regulation of estrogen-dependent sexual development of rat brain by growth factors

Intraventricular infusion of antiserum to nerve growth factor (ANGF), but not that to insulin, epidermal growth factor nor normal rabbit serum, resisted estrogen-induced behavioral defeminization in the female rat neonates. A significant number of the ANGF-treated rats showed lordosis as adults despite neonatal estrogen, but positive feedback of estrogen on serum luteinizing hormone was absent. Sexual phenotype in behavioral and gonadotropic functions may be under differential development regulation.