Summary evaluations of risk factors related to infant mortality

The authors discuss risk factors related to infant mortality. "The size and magnitude of these risk factors vary across different countries and regions. In order to more accurately describe the relationship between risk factors and infant mortality, risk factors should be quantified, making it possible to estimate the degree of risk associated with infant deaths. This article introduces some risk factors and their evaluation method."

Activated caspase 3 and cleaved poly(ADP-ribose)polymerase in salivary epithelium suggest a pathogenetic mechanism for Sjögren's syndrome

OBJECTIVE

Apoptosis is an organized energy-dependent process of cellular self-destruction carried out by proteolytic enzymes such as the caspases. These enzymes may play a role in epithelial cell apoptosis in Sjögren's syndrome (SS). A classical caspase substrate is poly(ADP-ribose)polymerase (PARP), a DNA repair enzyme. To elucidate the molecular mechanisms responsible for salivary gland dysfunction in SS, we studied the expression of caspase and PARP in SS salivary gland biopsies.

METHODS

The presence of activated caspases (caspases 3 and 9) and cleaved PARP (85 kDa) in SS biopsies was demonstrated by immunohistochemistry using specific polyclonal antibodies.

RESULTS

Initial studies performed with an antibody reagent that recognizes both active and inactive forms of caspase 3 identified this enzyme in SS salivary ductal and acinar cells. Activated caspase 3 and cleaved PARP were strongly expressed in ductal and acinar cells in SS salivary glands (13/15). Ductal and acinar cells from normal salivary glands (n=5) stained with less intensity compared with SS tissue. Staining for activated caspase 9 was negative in all samples. Likewise, infiltrating lymphocytes were negative for caspase 3, caspase 9 and cleaved PARP.

CONCLUSION

This study shows that caspase 3 is important in the salivary dysfunction of SS, while caspase 9 appears not to be involved.

Effects of radiation on Ca2+signaling in salivary epithelial cell lines transfected with Bcl-2 and Bcl-XL

The effects of radiation on the Ca2+ signaling system in HSY cells transfected with the Bcl-2 or Bcl-XL gene were studied. Bcl-2 overexpression did not alter carbachol (CCh)-elicited initial increase in cytosolic free Ca2+ concentrations ([Ca2+]i), but Bcl-XL overexpression dramatically reduced this response. Exposure to 10 Gy gamma-ray did not alter basal [Ca2+]i. By contrast, the CCh-stimulated initial [Ca2+]i increase was reduced at 0.5 and 4 h post-irradiation in all cell types and remained decreased at 24 h in wild-type and control-transfected cells, but recovered in Bcl-2- and Bcl-XL-transfectants. The formation of inositol 1,4,5-trisphosphate (IP3) in response to CCh at 4-h post-irradiation was decreased in wild-type and control-transfected cells, but not in Bcl-2 and Bcl-XL transfectants. The capacity of the IP3-sensitive Ca2+ store was significantly reduced by radiation in all cells except Bcl-XL transfectants. Ca2+ influx after stimulation with CCh was suppressed by exposure to radiation in wild-type and control-transfected cells, but not in Bcl-2- and Bcl-XL-transfectants. However, radiation enhanced Ca2+ influx activated by thapsigargin in all cell types. These results suggest that 1) radiation diminishes IP3 formation and Ca2+ release in response to CCh, but potentiates the store-operated Ca2+ influx; and 2) overexpression of Bcl-2 or Bcl-XL partially protects cells from radiation-induced inhibition of Ca2+ signaling.

Fas-mediated apoptosis in a rat acinar cell line is dependent on caspase-1 activity

Apoptosis plays an important role in the dysfunction of exocrine glands. Fas is a death-inducing receptor found on many types of cells including epithelial acinar cells. To elucidate the intracellular mechanism of Fas-mediated cell death in exocrine glands, an epithelial acinar cell line, SMG-C6, was studied. Caspase-1, -3, -8, and -9 activities were elevated in SMG-C6 cells after the induction of apoptosis by soluble Fas ligand (FasL). The activation of caspase-1 and -8 occurred prior to caspase-3 and -9 activation. The caspase-1 inhibitor, zYVAD-fmk, was effective in preventing cell death, whereas the caspase-3 and -8 inhibitors (ac-DEVD-CHO and ac-IETD-CHO, respectively) were not. zYVAD-fmk was able to inhibit caspase-3 activation indicating that caspase-1 is upstream to caspase-3. Furthermore, kinetic studies show that caspase-1 is an early event in the Fas apoptotic pathway. This study shows that caspase-1 participates in Fas-mediated apoptosis of epithelial cells by initiating the caspase cascade.

Steps to demarcate the effects of chromophore aggregation and planarization in poly(phenyleneethynylene)s. 2. The photophysics of 1,4-diethynyl-2-fluorobenzene in solution and in crystals

Crystals of 1,4-bis(2-hydroxy-2-methyl-3-butynyl)-2-fluorobenzene 4 have a rich packing structure with four distinct molecules in the unit cell. A complex hydrogen bonding network results in the formation of cofacial trimers, cofacial dimers, and monomers within the same unit cell. Given a remarkable opportunity to investigate the effect of aggregation on the photophysics of 1,4-diethynylbenzenes, we analyzed the absorption, diffuse reflectance, and emission spectra of compound 4 in solutions and in crystals. Diffuse reflectance and fluorescence excitation revealed a red-shifted absorption that is absent in dilute solution but becomes observable at high concentrations and low temperatures. The fluorescence emission in the solid state is dual with components assigned to monomers and aggregates. The excitation and emission assigned to the monomer are nearly identical in crystals and dilute solutions. The absorption and emission bands assigned to aggregates are broad and red-shifted by 60--80 nm. As expected for a sample with absorbers and emitters with different energies and incomplete equilibration, efficient monomer-to-aggregate energy transfer was observed by a proper selection of excitation wavelengths. The fluorescence quantum yield of 4 in solution is relatively low (Phi(F) = 0.15) and the singlet lifetime short (tau(F) = 3.8 ns). A lower limit for the triplet yield of Phi(T) = 0.64 was determined indirectly in solution by (1)O(2) sensitization, and a relatively strong and long-lived phosphorescence was observed in low-temperature glasses and in crystals at 77 K.

TGF-beta1 null mutation leads to CD154 upregulated expression in affected tissues

The TGF-beta1(-/-) mouse is a murine model for systemic autoimmune disease. The aim of this study is to elucidate the immunological mechanism that leads to multifocal tissue inflammation and autoantibody production in TGF-beta1(-/-) mice. Heart, lung, liver, and salivary gland from TGF-beta1(-/-) were assessed for CD154 expression by RT-PCR and immunohistochemistry. Compared to wild-type littermates, CD154 expression was elevated in all tissues studied. Furthermore, IL-12 mRNA was expressed in the salivary gland and heart of TGF-beta1(-/-) mice and not in wild-type littermates. This suggests that the CD154 pathway is activated in these tissues. This shows that TGF-beta1 regulates CD154 expression leading to spontaneous IL-12 production and autoimmunity.

Functional pleiotropy of an intramolecular triplex-forming fragment from the 3'-UTR of the rat Pigr gene

A microsatellite-containing 359-bp restriction fragment, isolated from the rat Pigr gene (murine polymeric immunoglobulin receptor gene) 3'-untranslated region (3'-UTR) and inserted into 3'-UTR or 3' flanking positions in transcription units of supercoiled plasmids, attenuates luciferase reporter gene expression in orientation- and position-dependent ways following transient transfection of human 293 cells. The same fragment stimulates orientation-dependent gene expression in a 5' flanking position. Plasmid linearization abrogates both orientation- and position-dependent responses. Cell-free translation reveals that 5' and 3' flanking expression responses are proportional to increased and decreased luciferase mRNA levels, whereas 3'-UTR expression is associated with control mRNA levels. Hypersensitivity to nucleases S1 and P1, gel mobility differences between supercoiled plasmids carrying opposing microsatellite orientations, and anomalous melting profiles of this fragment are also observed. These results suggest that functional pleiotropy of this fragment depends on the DNA context of its purine-rich microsatellite strand and on DNA supercoiling. Intramolecular triplexes stabilized by supercoiling and secondary structures of purine repeat-rich mRNAs may also confer regulatory properties to similar genomic elements.

Elevated proapoptotic Bax and caspase 3 activation in the NOD.scid model of Sjögren's syndrome

OBJECTIVE

Salivary gland epithelial cells in patients with Sjögren's syndrome (SS) and in NOD and NODscid mice express Fas and Fas ligand, and these cells die from apoptosis. To elucidate the intracellular molecular mechanisms responsible for this salivary gland epithelial cell apoptosis, expression of the Bcl-2 family of proteins (Bcl-2, Bcl-xL, Bax) and caspase (caspases 3 and 8) was studied in young (ages 8-10 weeks) and old (ages 17-28 weeks) NOD and NOD.scid mice.

METHODS

Sections of frozen salivary gland tissue were obtained from NOD and NOD.scid mice and from the lip biopsy material of SS patients. Immunohistochemistry or Western blot analysis was performed to assess the apoptotic-associated proteins.

RESULTS

Levels of Bax and caspase 3 were elevated in the epithelial cells of glands from old NOD mice, but not in those from young NOD mice. In contrast, epithelial cells from both young and old NOD.scid mice exhibited strong expression of Bax and caspase 3. Western blot analysis showed that the activated form of caspase 3 was increased 2-5-fold in the glands from old NOD, old NOD.scid, and young NOD.scid mice compared with those from young NOD mice. Caspase 3 was also significantly elevated (P < 0.01) in SS patients whose focus scores were grade 3 or 4. In the SS patients' biopsy tissue and in the mouse glands, cells with fragmented DNA were positive for caspase 3.

CONCLUSION

These results demonstrate that salivary gland epithelial cells in NOD and NOD.scid mice overexpress the proapoptotic molecules Bax and caspase 3. Bax could be the gene responsible for initiation of caspase activation, epithelial cell destruction, and lymphocyte glandular localization in SS.

Point mutant mice with hypersensitive alpha 4 nicotinic receptors show dopaminergic deficits and increased anxiety

Knock-in mice were generated that harbored a leucine-to-serine mutation in the alpha4 nicotinic receptor near the gate in the channel pore. Mice with intact expression of this hypersensitive receptor display dominant neonatal lethality. These mice have a severe deficit of dopaminergic neurons in the substantia nigra, possibly because the hypersensitive receptors are continuously activated by normal extracellular choline concentrations. A strain that retains the neo selection cassette in an intron has reduced expression of the hypersensitive receptor and is viable and fertile. The viable mice display increased anxiety, poor motor learning, excessive ambulation that is eliminated by very low levels of nicotine, and a reduction of nigrostriatal dopaminergic function upon aging. These knock-in mice provide useful insights into the pathophysiology of sustained nicotinic receptor activation and may provide a model for Parkinson's disease.

G-protein signaling abnormalities mediated by CD95 in salivary epithelial cells

Salivary epithelial cells from patients with primary Sjögren's syndrome (SS) undergo Fas-mediated apoptosis. Bcl-2 and Bcl-xL are apoptosis suppressing oncogenes. Very little is known about the role of these oncogene molecules in salivary epithelial cells. To investigate the possible prevention of salivary glandular destruction in SS by Bcl-2 and Bcl-xL, stable transfectants expressing these molecules were made from HSY cells, a human salivary epithelial cell line. HSY cells were transfected with an expression vector for human Bcl-2 or Bcl-xL. Stable transfectants were selected and apoptosis was induced by anti-Fas antibody. Apoptosis was quantified by propidium iodide staining followed by flow cytometry. Caspase activity was detected by immunohistochemical analysis and enzyme cleavage of DEVD-AMC, a fluorescent substrate. Response to carbachol, a muscarinic receptor agonist, and EGF was measured by Ca2+ mobilization and influx. Fas-mediated apoptosis was significantly inhibited in Bcl-2 and Bcl-xL transfectants compared to wild-type and control transfectants (empty vector). Surprisingly, caspase activity was not inhibited in Bcl-2 and Bcl-xL transfectants. Activation of the Fas pathway in the Bcl-2 and Bcl-xL transfectants by antibody also inhibited carbachol and EGF responsiveness (i.e., Ca2+ mobilization and/or influx) by 50-60%. This Fas-mediated inhibition of cell activation was partially or completely restored by specific peptide interference of caspase enzyme activity. The prevention of Fas-mediated apoptosis by the overexpression of Bcl-2 and Bcl-xL in salivary gland epithelial cells results in injured cells expressing caspase activity and unable to respond normally to receptor agonists. Such damaged cells may exist in SS patients and could explain the severe dryness out of proportion to the actual number of apoptotic cells seen on salivary gland biopsy.

[Clinical results of transmyocardial laser revascularization for 77 patients with coronary artery disease]

OBJECTIVE

To analyses the clinical results of transmyocardial laser revascularization (TMLR) for 77 patients with coronary artery diseases (CAD).

METHODS

The mean age of the patients was (65 +/- 7) years. Previous medical record included CABG (6 patients), PTCA (9), AMI (66.2%), hypertension (70.1%), and diabetes mellitus (45.5%). TMLR was performed on the beating heart via a left anterolateral thoracotomy at the fifth intercostal space. Transesophageal echocardiography showed transmyocardial penetration of 23 +/- 6 channels.

RESULTS

The hospital mortality was 3.8%, and postoperative complications were AMI (3.8%), left ventricular failure (2.6%), PVC (5.2%). After operation, the mean CCS angina class was improved from the baseline 3.5 +/- 0.7 to 2.1 +/- 0.3 at 3 months, 1.7 +/- 0.3 at 6 months, 1.7 +/- 0.3 at 12 months and 1.8 +/- 0.4 at 24 months. One patient died of AMI and two died not due to cardiac events during a follow-up of 3 to approximately 24 months. Echocardiography showed that the average of left ventricular ejection fractions was improved significantly at 6 months after operation compared with the preoperative value (P = 0.0457). (201)TI-SPECT showed a remarkable improvement in reversible ischemia in 70% patients followed up. Metabolic stress test for 20 patients followed up patients demonstrated an average increase in exercise tolerance from 7.1 +/- 3.2 min at the baseline to 9.6 +/- 1.3 min at 12 months (P = 0.021). Similarly the METs increased from 4.3 +/- 2.1 at the baseline to 5.4 +/- 2.0 at 12 months.

CONCLUSIONS

TMLR is a safe and effective procedure for the treatment of end stage coronary artery diseases not amenable to PTCA or CABG. The effect of TMLR is associated with indication, correct evaluation of myocardial ischemia, and management for postoperative complications.

The status of immunization measurement and feedback in the United States

BACKGROUND

A large body of scientific and programmatic data has demonstrated that provider measurement and feedback raises immunization coverage. Starting in 1995, Congress required that all states measure childhood immunization coverage in all public clinics, and federal grant guidelines encourage private practice measurements.

OBJECTIVES

To determine state immunization measurement rates and examine risk factors for high rates.

METHODS

Review of 1997 state reports, with correlation of measurement rates to birth cohort and provider numbers, public/private proportions, and vaccine distribution systems.

RESULTS

Of the 9505 public clinics, 48% were measured; 4 states measured all clinics; 29 measured a majority. Measurement rates were highest for Health Department clinics (67%), lower for community/migrant health centers (39%), and lowest for other clinics (22%). Rates were highly correlated among categories of clinics (r>+0.308, P<.03), and the fewer the clinics, the higher the measurement rates (r = -0.351, P =. 01), but other factors were not significant. Of the 41,378 private practices, 6% were measured; no state measured all its practices; 1 measured a majority. Private practice measurement rates were not correlated to public clinic measurement rates or other factors examined. Of the 50,883 total providers, 14% were measured; no state measured all providers; 2 measured a majority. A trend toward higher measurement rates was found in states with fewer providers (r = -0. 266, P =.06).

CONCLUSIONS

Three years after the congressional mandate, only a minority of public clinics and very few private practices had their immunization coverage measured. Greater efforts will be needed to assure implementation of the intervention. Arch Pediatr Adolesc Med. 2000;154:832-836

Probing the role of a conserved M1 proline residue in 5-hydroxytryptamine(3) receptor gating

A conserved proline residue is found in the first transmembrane domain (M1) of every subunit in the ligand-gated ion channel superfamily. The position of this proline between the N-terminal extracellular agonist binding and the second transmembrane (M2) channel lining domains in the primary sequence suggests its possible involvement in the gating of the receptor. Replacing this proline with alanine, glycine, or leucine in the 5-hydroxytryptamine (5-HT)(3A) homomeric receptors expressed in Xenopus laevis oocytes resulted in the absence of 5-HT-induced whole-cell currents, although there were normal levels of specific surface [(3)H]granisetron ([(3)H]BRL-43694) binding sites. To determine what properties of the conserved proline are critical for the function of the channel, two imino acids and an alpha-hydroxy acid were incorporated at the proline position using the nonsense suppression method. trans-3-Methyl-proline, pipecolic acid, and leucic acid were able to replace the conserved proline to produce active channels with EC(50) values similar to that for the wild-type receptor. These trends are preserved in the heteromeric receptors consisting of 5-HT(3A) and 5-HT(3B) subunits in oocytes. The prominent common feature among these residues and proline is the lack of hydrogen bond donor activity, potentially resulting in a flexible secondary structure in the M1 region. Thus, lack of hydrogen bond donor activity may be a key element in channel gating and may explain the high degree of conservation of this M1 proline.

Mice homozygous for the L250T mutation in the alpha7 nicotinic acetylcholine receptor show increased neuronal apoptosis and die within 1 day of birth

The alpha7 nicotinic acetylcholine receptor (nAChR) has been implicated in modulating neurotransmitter release and may play a role in the regulation of neuronal growth and differentiation. A threonine for leucine 247 substitution in the channel domain of the chick alpha7 nAChR increases agonist affinity and decreases the rate of desensitization, creating a "gain of function" model for this receptor. We have generated mice that express the analogous mutation (L250T) in the alpha7 nAChR using the techniques of homologous recombination and here report their characteristics. Mice heterozygous (+/T) for the L250T mutation are viable, fertile, and anatomically normal compared with wild-type littermates. In contrast, homozygous (T/T) L250T mice die within 2-24 h of birth. Brains of T/T mouse pups exhibit a marked reduction in alpha7 nAChR protein levels and show extensive apoptotic cell death throughout the somatosensory cortex. Furthermore, alpha7 L250T nAChRs are functionally expressed on neurons within the brains of T/T neonatal mice and have properties that are consistent with those observed for the rat alpha7 L250T and the chick alpha7 L247T mutant nAChRs expressed in oocytes. These findings indicate that neurons in the developing brain expressing only alpha7 L250T mutant nAChRs are susceptible to abnormal apoptosis, possibly due to increased Ca2+ influx.

Bacterial primary colonization and early succession on surfaces in marine waters as determined by amplified rRNA gene restriction analysis and sequence analysis of 16S rRNA genes

The nearly universal colonization of surfaces in marine waters by bacteria and the formation of biofilms and biofouling communities have important implications for ecological function and industrial processes. However, the dynamics of surface attachment and colonization in situ, particularly during the early stages of biofilm establishment, are not well understood. Experimental surfaces that differed in their degrees of hydrophilicity or hydrophobicity were incubated in a salt marsh estuary tidal creek for 24 or 72 h. The organisms colonizing these surfaces were examined by using a cultivation-independent approach, amplified ribosomal DNA restriction analysis. The goals of this study were to assess the diversity of bacterial colonists involved in early succession on a variety of surfaces and to determine the phylogenetic affiliations of the most common early colonists. Substantial differences in the representation of different cloned ribosomal DNA sequences were found when the 24- and 72-h incubations were compared, indicating that some new organisms were recruited and some other organisms were lost. Phylogenetic analyses of the most common sequences recovered showed that the colonists were related to organisms known to inhabit surfaces or particles in marine systems. A total of 22 of the 26 clones sequenced were affiliated with the Roseobacter subgroup of the alpha subdivision of the division Proteobacteria (alpha-Proteobacteria), and most of these clones were recovered at a high frequency from all surfaces after 24 or 72 h of incubation. Two clones were affiliated with the Alteromonas group of the gamma-Proteobacteria and appeared to be involved only in the very early stages of colonization (within the first 24 h). A comparison of the colonization patterns on the test surfaces indicated that the early bacterial community succession rate and/or direction may be influenced by surface physicochemical properties. However, organisms belonging to the Roseobacter subgroup are ubiquitous and rapid colonizers of surfaces in coastal environments.

Monocyte rescue of human T cells from apoptosis is CD40/CD154 dependent

The induction of T-cell apoptosis is regulated in part by monocytes (CD14+ cells). Human peripheral blood monocytes inhibited the spontaneous cell death of activated T cells in vitro. The inhibition of T-cell apoptosis did not require autologous monocytes. Inhibition required direct contact with monocytes and was not due to a soluble factor. Furthermore, treatment of monocytes with actinomycin D, cycloheximide and paraformaldehyde abrogated the anti-apoptotic activity of these cells. Blocking antibody to CD40 and CD154 (CD40 ligand) decreased the ability of monocytes to aid in T-cell survival, whereas, blocking LFA-1/I-CAM-1, Fas ligand and the CD4/major histocompatibility complex class II interaction did not affect the influence of monocytes on T-cell survival. This shows that monocytes rescue of activated T cells from apoptosis is dependent upon CD40/CD154 interaction.

Binding of nuclear proteins to the negative regulatory element of the IL-2 gene in lymphocytes from rheumatic patients

T lymphocytes from several autoimmune diseases including rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) exhibit deficient mitogenic response in terms of proliferation and IL-2 production. The expression of the IL-2 gene is regulated by various transcription factors. One of these factors suppresses IL-2 expression and binds to the negative responsive element in the IL-2 gene 5' flanking region (NRE-A). The authors hypothesized that the decreased production of IL-2 by T cells from RA and SLE patients is at least partially caused by high expression of the NRE-A binding protein. To test this hypothesis T cells from healthy donors and patients with RA and SLE were stimulated. Using the electrophoretic mobility shift assay we detected NRE-A DNA-binding proteins in the nuclei of the stimulated cells. No difference was found between NRE-A DNA binding in nuclear extracts of T cells taken from healthy donors and those taken from patients. The specificity of the DNA-protein interactions was ascertained through the use of unlabeled DNA competitors. No correlation was found between DNA-binding and the patients' disease duration or medication. In conclusion, decreased IL-2 biosynthesis by T lymphocytes from RA and SLE patients can not be explained by abnormal expression of the NRE-A DNA-binding protein.

Inappropriate apoptosis of salivary and lacrimal gland epithelium of immunodeficient NOD-scid mice

OBJECTIVE

The lesion is Sjögren's syndrome consists of lymphocytic infiltration and has a pathology characteristic of the potential apoptotic death of salivary gland secretory epithelial cells. To examine the role of the glandular epithelial cells in the pathogenesis of autoimmune exocrinopathy, we studied Fas and Fas ligand (FasL) expression and quantitated the levels of apoptosis in salivary and lacrimal glands from NOD and NOD-scid mice, an animal model that develops a Sjögren's syndrome-like pathology.

METHODS

The parotid, submandibular and lacrimal tissues of NOD, NOD-scid, and BALB/c mice were evaluated by immunohistochemical analysis for the expression of Fas and FasL. Nuclear fragmentation of DNA from the epithelial cells of exocrine tissues was evaluated by the terminal UTP nucleotide end labeling method (TUNEL). Messenger RNA was isolated from 8 and 18 week old mice and was analyzed by the reverse transcription-polymerase chain reaction (RT-PCR) for the expression of Fas and FasL.

RESULTS

We found suggestive evidence that apoptosis of the secretory epithelial cells occurs in both NOD and NOD-scid mice despite the lack of T- and B-lymphocytes in the latter. FasL mRNA and cell surface protein were expressed in salivary and lacrimal gland epithelial cells from 8 and 18 week old NOD, NOD-scid, and BALB/c mice. Fas protein and mRNA were expressed only in the exocrine glands from 18 week old NOD and NOD-scid mice. Glandular secretory epithelial cell apoptosis was elevated in both NOD and NOD-scid mice, however; there was little evidence of apoptosis in the control strain of BALB/c mice.

CONCLUSION

These results suggest a potential apoptotic process dependent on Fas:FasL interactions occurring in NOD-scid glandular secretory epithelial cells in the absence of lymphocytic infiltration.

Fas (CD95)-transduced signal preferentially stimulates lupus peripheral T lymphocytes

Fas (CD95) is a cell surface receptor whose biological function in circulating peripheral T cells is not well understood. To address the question of abnormal T cell sensitivity to Fas stimulation in systemic lupus erythematosus (SLE), we studied Fas-transduced stimulation and apoptosis in peripheral blood T cells from patients with SLE and normal control. Immobilized anti-Fas monoclonal antibodies (mAb) (imCH-11; IgM type) significantly stimulated SLE T cell proliferation compared to T cells from normal donors and patients with rheumatoid arthritis (p < 0.003 and p < 0.005, respectively). The soluble form of CH-11 and other immobilized anti-Fas mAb (UB-2, ZB-4; IgG type) failed to stimulate lupus T cells while immobilized human Fas ligand did. Furthermore, imCH-11 induced IL-2 and IL-6 mRNA expression. However, imCH-11 activation failed to induce expression of the T cell activation surface molecules CD25 and CD69. Addition of exogenous ceramide, a second messenger for Fas-mediated apoptosis signaling, also induced T cell proliferation in SLE and normal controls. Moreover, fumonisin B1, a specific ceramide synthase inhibitor, and caspase inhibitors markedly suppressed imCH-11 induced T cell proliferation, suggesting that the ceramide pathway may be involved in Fas-transduced stimulation signals in SLE T cells. These results show that SLE T cells have an alteration in the Fas signal transduction pathway leading to cell proliferation. This defect may be important in Fas-mediated peripheral immune homeostasis.

Bcl-2 family expression in salivary glands from patients with primary Sjögren's syndrome: involvement of Bax in salivary gland destruction

To investigate the molecular mechanism of glandular parenchyma destruction in Sjögren's syndrome (SS), Bcl-2, Bax, Bcl-X, and Bak expression were studied. SS (n = 18) and control salivary glands (n = 6) were examined by immunohistochemistry. Apoptosis was assessed by in situ DNA nick end labeling. Infiltrating mononuclear cells in the SS salivary gland showed elevated Bcl-2. These mononuclear cells expressed increased Bax but did not undergo apoptosis. Both SS and control salivary gland ductal epithelial cells expressed Bcl-2, Bax, and Bcl-X. SS, but not normal, salivary gland acinar cells expressed Bax and underwent apoptosis. These results suggest that elevated Bax expression in SS salivary gland acinar cells may play an important role in the apoptotic pathway. In contrast, Bcl-2 expression in SS infiltrating mononuclear cells and ductal cells may contribute to their survival.

CD4 mononuclear cell infiltrates and Fas/Fas ligand positive mammary gland cells in breast tissue from a patient with Sjögren's syndrome

We describe a 49-year-old patient with lip biopsy proven Sjögren's syndrome (SS) and keratoconjunctivitis sicca, who had dental caries, xerostomia, recurrent upper respiratory tract infections, arthritis in her hands, elbows and knees, and recurrent parotid inflammation. She developed bilateral breast nodules in 1988. Right breast nodules were excised in 1993 and 1995, but reappeared in 1996, requiring 2 more excisions. Breast tissue samples showed remarkable intralobular and perilobular mononuclear cell infiltrates that were predominantly CD4+ T cells and expressed bcl-2. A few cells stained CD20+ and CD8+. SS breast glandular epithelial cells stained more intensely for Fas compared to normal cells. CD4+ T cells and Fas mediated cell death may be involved in the mammary gland lesions in SS.

Alpha1A-adrenergic receptors mediate vasoconstriction of the isolated spiral modiolar artery in vitro

Several lines of evidence suggest that cochlear blood flow is under the control of the sympathetic nervous system and that this control is mediated via alpha-adrenergic receptors. The goal of the present study was to determine whether alpha-adrenergic receptors mediate vasoconstriction of the spiral modiolar artery and, if so, to determine which subtype dominates this response. Vascular diameter was measured with video microscopy in the isolated superfused spiral modiolar artery in vitro. The diameter of the spiral modiolar artery under control conditions was 61 +/- 2 microm (n = 60). Spontaneous vasomotion was observed in most specimens. Addition of norepinephrine to the superfusate caused a phasic vasoconstriction and an increase in the amplitude of vasomotion. These effects were limited to the vicinity of arteriolar branch points of the spiral modiolar artery. Norepinephrine-induced vasoconstriction occurred with EC50 of (1.9 +/- 0.4) x 10(-5) M (n = 44) and the vascular diameter was maximally reduced by a factor of 0.87 +/- 0.01 (n = 29). Neither the phasic nature nor the EC50 of the norepinephrine-induced vasoconstrictions was altered in the presence of the beta2-adrenergic receptor antagonist 10(-5) M ICI118551 or the nitric oxide synthase inhibitor 10(-4) M NOARG. In contrast, the alpha2-adrenergic receptor antagonist 10(-7) M yohimbine and the alpha1-adrenergic receptor antagonist 10(-9) and 10(-8) M prazosin caused a significant shift in the dose-response curve. The affinity constants (K(DB)) for yohimbine and prazosin were (5+/-2) x 10(-8) M (n=4) and (2.0+/-0.7) x 10(-10) M (n=18), respectively. The alpha1A-adrenergic receptor antagonist 10(-8) M 5-methyl urapidil and the alpha1D-adrenergic receptors antagonist 5 x 10(-6) M BMY7378 caused a significant shift in the dose-response curve. The K(DB) values for 5-methyl urapidil and for BMY7378 were (2.7 +/- 0.7) x 10(-10) M (n = 8) and (4.4 +/- 2.7) x 10(-7) M (n = 8), respectively. Further, total RNA was isolated from microdissected spiral modiolar arteries and the presence of transcripts for alpha1-adrenergic receptor subtypes was determined by reverse transcription polymerase chain reaction (RT-PCR). Primers specific for gerbil alpha1-adrenergic receptor subtypes were developed using RNA from rat and gerbil brain. Analysis of RNA extracted from the spiral modiolar artery revealed RT-PCR products of the appropriate size for the alpha1A-adrenergic receptor, however, no evidence for the alpha1B- and alpha1D-adrenergic receptor was found. Further, analysis of RNA extracted from blood, which was a contaminant of the microdissected spiral modiolar arteries, revealed no RT-PCR products. Sequence analysis of the RT-PCR product of the alpha1A-adrenergic receptor from the spiral modiolar artery confirmed its identity. Identity between the 175 nt gerbil sequence fragment and the known rat, mouse and human alpha1A-adrenergic receptor sequences was 90.9, 92.0 and 85.2%, respectively. These observations demonstrate that the spiral modiolar artery contains alpha1A-adrenergic receptors which mediate vasoconstriction at branch points.

[Alteration of fatty acid components of erythrocyte membrane and insulin resistance in diabetic patients]

OBJECTIVE

To study the effect of alteration of erythrocyte membrane fatty acid components and fluidity on insulin resistance (ISR) in NIDDM patients.

METHODS

The fatty acid(FA) components and fluidity of erythrocyte membrane in 52 NIDDM patients with and without hyper-insulinemia were examined by a high-performance liquid chromatographic method and flourescence polarization technique.

RESULTS

The content and composition erythrocyte membrane arachidonate (AA) were significantly lower in NIDDM patients than in controls, and also markedly lower in patients with hyperinsulinemia than those without hyperinsulinemia. The diabetics had increased erythrocyte membrane microviscosities as compared with controls, and membrane microviscosities were higher in diabetics with hyperinsulinemia than those without hyperinsulinemia. AA contents of erythrocyte membrane were negatively correlated with membrane membrane microviscosities and positively with ISI in NIDDM patients.

CONCLUSION

In NIDDM patients, hyperinsulinemia and ISI bring about AA metabolic abnormalities and decreased AA contents in cell membrane. Alteration of cell membrane FA components results in the changes of membrane fluidity, and the latter can increase IRS.

Contributions of N-linked glycosylation to the expression of a functional alpha7-nicotinic receptor in Xenopus oocytes

The alpha7 subunit of the neuronal nicotinic acetylcholine receptor, when expressed in Xenopus oocytes, forms homooligomeric ligand-gated ion channels that are blocked by a snake toxin, alpha-bungarotoxin. The amino-terminal extracellular domain of the alpha7 sequence has three consensus sites for asparagine-linked glycosylation (N46DS, N90MS, and N133AS). In this study, we show that alpha7 expressed either in vivo or in vitro is a glycoprotein of 57 kDa. In addition, we demonstrate by site-directed mutagenesis that all three consensus sites are used for glycosylation. To elucidate the role(s) of asparagine-linked glycosylation in the formation and function of the alpha7 receptor, wild-type and glycosylation-deficient alpha7 subunits were expressed in COS cells and oocytes. We examined biochemical and physiological properties of expressed receptors and found that alpha7 glycosylation mutations do not affect homooligomerization and surface protein expression of the alpha7 receptor but do affect surface expression of alpha-bungarotoxin binding sites and the function of the receptor. Our data indicate that asparagine-linked glycosylation is required for the expression of a functional alpha7 receptor in oocytes.

Strangulated traumatic diaphragmatic hernia simulating a subphrenic abscess

Traumatic diaphragmatic hernias can be difficult to diagnose because of their varied clinical and radiologic signs and because patients may not present with symptoms for months to years following the injury. We report a case of a delayed presentation of a traumatic diaphragmatic rupture through which a portion of the stomach herniated and simulated a large subphrenic abscess.

Flow cytometric detection of Cryptosporidium oocysts in human stool samples

Cryptosporidium parvum is an important pathogen that causes diarrhea in virtually all human populations. Improved diagnostic methods are needed to understand the risk factors, modes of transmission, and impact of cryptosporidiosis. In the present study, we fluorescently labeled and counted C. parvum oocysts by flow cytometry (FC) and developed a simple and efficient method of processing human stool samples for FC analysis. Formed stool (suspended in phosphate-buffered saline) from an asymptomatic, healthy individual was seeded with known concentrations of oocysts, and oocysts were labeled with a cell wall-specific monoclonal antibody and detected by FC. The method described herein resulted in a mean oocyst recovery rate of 45% +/- 16% (median, 42%), which consistently yielded a fourfold increase in sensitivity compared to direct fluorescent-antibody assay of seeded stool samples. However, in many instances, FC detected as few as 10(3) oocysts per ml. Thus, FC provides a reproducible and sensitive method for C. parvum oocyst detection.

Up-regulation of cytokine mRNA, adhesion molecule proteins, and MHC class II proteins in salivary glands of TGF-beta1 knockout mice: MHC class II is a factor in the pathogenesis of TGF-beta1 knockout mice

Mice homozygous for a disrupted TGF-beta1 allele develop multiple lymphoproliferative disorders similar to those seen in the pseudolymphoma of Sjögren's syndrome. At 2 wk of age, these TGF-beta1 mutant mice begin to develop wasting syndrome and die at around 4 to 5 wk of age. We studied salivary glands from symptomatic mutant mice &gt;14 days of age. Reverse transcriptase-PCR analysis showed up-regulation of proinflammatory cytokine genes such as IL-1alpha, IL-1beta, IL-2, IL-4, IL-6, IL-10, and IFN-gamma in these mutant mice. Enhanced expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM-1), and MHC class II as well as CD4-positive T lymphocyte infiltration was detected by immunostaining. To elucidate the role of MHC class II, salivary glands from TGF-beta1/MHC class II double knockout mice were used to investigate the expression of adhesion molecules and MHC class II. In spite of the existence of basal intercellular adhesion molecule-1 expression on vessels, there was neither MHC class II expression, enhanced vascular cell adhesion molecule-1 expression, nor lymphocytic infiltration in the salivary glands. These results suggest that MHC class II plays a significant role in the pathogenesis of TGF-beta1 mutant mice. Although the mechanism that initiates multiple inflammatory diseases in these mice remains unclear, the context reported here would provide insight into the immunopathology of Sjögren's syndrome.

Up-regulation of cytokine mRNA, adhesion molecule proteins, and MHC class II proteins in salivary glands of TGF-beta1 knockout mice: MHC class II is a factor in the pathogenesis of TGF-beta1 knockout mice

Mice homozygous for a disrupted TGF-beta1 allele develop multiple lymphoproliferative disorders similar to those seen in the pseudolymphoma of Sjögren's syndrome. At 2 wk of age, these TGF-beta1 mutant mice begin to develop wasting syndrome and die at around 4 to 5 wk of age. We studied salivary glands from symptomatic mutant mice >14 days of age. Reverse transcriptase-PCR analysis showed up-regulation of proinflammatory cytokine genes such as IL-1alpha, IL-1beta, IL-2, IL-4, IL-6, IL-10, and IFN-gamma in these mutant mice. Enhanced expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM-1), and MHC class II as well as CD4-positive T lymphocyte infiltration was detected by immunostaining. To elucidate the role of MHC class II, salivary glands from TGF-beta1/MHC class II double knockout mice were used to investigate the expression of adhesion molecules and MHC class II. In spite of the existence of basal intercellular adhesion molecule-1 expression on vessels, there was neither MHC class II expression, enhanced vascular cell adhesion molecule-1 expression, nor lymphocytic infiltration in the salivary glands. These results suggest that MHC class II plays a significant role in the pathogenesis of TGF-beta1 mutant mice. Although the mechanism that initiates multiple inflammatory diseases in these mice remains unclear, the context reported here would provide insight into the immunopathology of Sjögren's syndrome.

Fas and Fas ligand expression in the salivary glands of patients with primary Sjögren's syndrome

OBJECTIVE

To assess the role of Fas-mediated apoptosis in the salivary glands of patients with primary Sjögren's syndrome (SS).

METHODS

Expression of Fas, Fas ligand (FasL), and bcl-2 in salivary gland biopsy material was detected in situ by immunohistochemical staining and reverse transcriptase-polymerase chain reaction. DNA fragmentation in apoptotic cells was assessed by the enzymatic incorporation of labeled nucleotides (digoxigenin-dUTP).

RESULTS

The acinar epithelial cells in SS were Fas+ and FasL+, and these cells died by apoptosis. The majority of infiltrating lymphocytes in SS were Fas+ and bcl-2+, while few lymphocytes expressed FasL. In situ detection of apoptosis showed minimal cell death of lymphocytes, particularly in dense periductal foci. Lymphocytic cell death was significantly lower (P < 0.0001) in these foci compared with that in the interstitium.

CONCLUSION

Infiltrating lymphocytes in the focal lesions of the salivary glands of patients with SS are blocked in their ability to commit to apoptosis, even though they may express Fas. The presence of bcl-2 in these cells may explain their inability to undergo apoptosis. The acinar epithelial cells, in contrast, may undergo Fas-mediated apoptosis. These results suggest that the Fas death pathway may be an important mechanism leading to the glandular destruction found in SS.

Lymphocyte apoptosis and apoptosis-associated gene expression in Sjögren's syndrome

OBJECTIVE

To study the mechanism and regulation of apoptosis in peripheral blood T and B lymphocytes from patients with Sjögren's syndrome (SS).

METHODS

The mode of in vitro lymphocyte death in the peripheral blood of patients with SS was determined by fluorescence microscopic analysis, terminal deoxynucleotidyl transferase assay, and DNA fragmentation analysis. Apoptotic cell death of T and B cells was determined at 48 hours of culture by fluorescence-activated cell sorter analysis of propidium iodidestained cells. Messenger RNA (mRNA) expression of bcl-2, bcl-x, bax, and c-myc in T and B cells was determined by enzyme-linked immunosorbent assay-polymerase chain reaction (ELISA-PCR). Expression of bcl-xL and bcl-xS was determined by Southern blot analysis of PCR products. Gene expression was calculated as the ratio of each gene message to the message of the GAPDH gene. Bcl-2 protein levels in SS T cells were determined by ELISA.

RESULTS

SS T cells showed increased in vitro apoptosis compared with normal T cells (mean +/- SD 12.3 +/- 4.5% versus 7.3 +/- 2.0%; P < 0.01). Freshly isolated SS T cells showed increased expression of bcl-2 mRNA compared with normal controls (mean +/- SD 1.50 +/- 0.65 versus 0.88 +/- 0.23; P < 0.05). There was no significant difference in levels of bax or c-myc mRNA in T cells and B cells between SS patients and normal controls. When SS T lymphocytes were cultured in vitro for 72 hours, Bcl-2 protein levels decreased with time.

CONCLUSION

SS T cells showed accelerated apoptosis in vitro. Freshly isolated SS T cells had increased expression of bcl-2. An increase in death-promoter signals and decrease in death-suppressor signals in vitro may have been responsible, in part, for the apoptosis in SS T lymphocytes.

Pooled human immunoglobulins contain anti-idiotypes with reactivity against the SLE-associated 4B4 cross-reactive idiotype

OBJECTIVE

To identify anti-idiotype antibody activity against a regulatory anti-Sm idiotype (4B4) in pooled human IgG (IVIG).

METHODS

ELISA were used to determine anti-idiotype antibody activity in IVIG.

RESULTS

Anti-idiotype antibody activity to 4B4 was detected in IVIG. The anti-idiotypic activity in IVIG could be inhibited by antigen, Sm, and rabbit anti-idiotypic antiserum. The idiotypic binding activity was predominately directed against the 4B4 VH region.

CONCLUSION

IVIG contains antibodies against a lupus-associated crossreactive idiotype. These antibodies represent Ab2 beta type antibodies. The anti-idiotypic activity in IVIG may be relevant to the efficacious use of IVIG in treating rheumatic diseases.

Autoimmunity associated with TGF-beta1-deficiency in mice is dependent on MHC class II antigen expression

The progressive inflammatory process found in transforming growth factor beta1 (TGF-beta1)-deficient mice is associated with several manifestations of autoimmunity, including circulating antibodies to nuclear antigens, immune complex deposition, and increased expression of both class I and class II major histocompatibility complex (MHC) antigens. The contribution of MHC class II antigens to the genesis of this phenotype has been determined by crossing the TGF-beta1-null [TGF-beta1(-/-)] genotype into the MHC class II-deficient [MHC-II(-/-)] background. Mice homozygous for both the TGF-beta1 null allele and the class II null allele [TGF-beta1(-/-);MHC-II(-/-)] are without evidence of inflammatory infiltrates, circulating autoantibodies, or glomerular immune complex deposits. Instead, these animals exhibit extensive extramedullary hematopoiesis with progressive splenomegaly and adenopathy, surviving only slightly longer than TGF-beta1(-/-);MHC-II(+/+) mice. The role of CD4+ T cells, which are also absent in MHC class II-deficient mice, is directly demonstrated through the administration of anti-CD4 monoclonal antibodies in class II-positive, TGF-beta1(-/-) mice. The observed reduction in inflammation and improved survival emphasize the significance of CD4+ cells in the pathogenesis of the autoimmune process and suggest that the additional absence of class II antigens in TGF-beta1(-/-);MHC-II(-/-) mice may contribute to their extreme myeloid metaplasia. Thus, MHC class II antigens are essential for the expression of autoimmunity in TGF-beta1-deficient mice, and normally may cooperate with TGF-beta1 to regulate hematopoiesis.

Abnormality of Oct-1 DNA binding in T cells from Sjögren's syndrome patients

Primary Sjögren's syndrome (SS) is an autoimmune rheumatic disease characterized by T cell hypoactivity. To understand the diminished T cell response to activation signals, we measured nucleoprotein DNA-binding activities regulating gene expression during T cell activation using the electrophoretic mobility shift assay. Peripheral blood lymphocytes from 9/19 SS patients were found to be defective in their ability to bind an october sequence (Oct-1). This Oct-1-binding phenotype remained stable in culture for up to 3 days prior to activation. This abnormality was not seen in resting T cells nor T cells from patients with systemic lupus erythematosus, rheumatoid arthritis (RA), or SS accompanied by RA. The SS Oct-1 DNA-binding abnormality correlated significantly with an inability of cells to exit the Gzero/G1 cell cycle phase when stimulated in vitro. Importantly, nucleoprotein extracts showing decreased DNA-binding activity had normal amounts of Oct-1 proteins as determined by immunoprecipitation, implying a functional defect in the Oct-1 protein. Moreover, defective DNA binding was corrected by treatment with acid phosphatase.

SLE-like autoantibodies and Sjögren's syndrome-like lymphoproliferation in TGF-beta knockout mice

Mice bearing the TGF-beta 1 null mutation (-/-) develop lymphoid infiltrates in the heart, lungs, salivary glands, and other organs similar to those seen in the pseudolymphoma of Sjögren's Syndrome. We studied sera from -/- mice and found elevated Ab levels to dsDNA, ssDNA, and Sm ribonucleoprotein. No Abs to SSA/Ro or SSB/La and no IgM rheumatoid factor were found. Serum autoantibodies were predominately IgG and were specific as shown by ELISA inhibition studies. Antinuclear Ab patterns on Western blots varied from one mouse to the next, indicating a random process responsible for the diversity. Wild-type and heterozygote mice had no autoantibodies. Ig glomerular deposits were found in -/- mice, indicating that these autoantibodies may be pathogenic. Treatment of -/- mice with dexamethasone or TGF-beta 1 failed to suppress autoantibody production. These mice represent an overlap combining the autoimmune serology of SLE with the tissue infiltrates of SS. Our results support the concept that TGF-beta 1 is an important naturally occurring immunosuppressive cytokine whose absence can lead to a systemic autoimmune disease.

SLE-like autoantibodies and Sjögren's syndrome-like lymphoproliferation in TGF-beta knockout mice

Mice bearing the TGF-beta 1 null mutation (-/-) develop lymphoid infiltrates in the heart, lungs, salivary glands, and other organs similar to those seen in the pseudolymphoma of Sjögren's Syndrome. We studied sera from -/- mice and found elevated Ab levels to dsDNA, ssDNA, and Sm ribonucleoprotein. No Abs to SSA/Ro or SSB/La and no IgM rheumatoid factor were found. Serum autoantibodies were predominately IgG and were specific as shown by ELISA inhibition studies. Antinuclear Ab patterns on Western blots varied from one mouse to the next, indicating a random process responsible for the diversity. Wild-type and heterozygote mice had no autoantibodies. Ig glomerular deposits were found in -/- mice, indicating that these autoantibodies may be pathogenic. Treatment of -/- mice with dexamethasone or TGF-beta 1 failed to suppress autoantibody production. These mice represent an overlap combining the autoimmune serology of SLE with the tissue infiltrates of SS. Our results support the concept that TGF-beta 1 is an important naturally occurring immunosuppressive cytokine whose absence can lead to a systemic autoimmune disease.

Analysis of transforming growth factor beta and other cytokines in autoimmune exocrinopathy (Sjögren's syndrome)

Cytokines play a major role in tissue destruction caused by autoimmune dysregulation. In Sjögren's syndrome (SS) patients, salivary glands are the target organs for autoimmune tissue damage. In the present study, reverse transcriptase-polymerase chain reaction (RT-PCR) was used to look for cytokine mRNA expressed in SS salivary glands. Focus score was used to determine the severity of the lesions. Cytokine production in supernatants of the salivary gland cell culture was measured by enzyme-linked immunosorbent assay (ELISA). Immunohistochemical staining was used to identify the local presence of transforming growth factor beta (TGF-beta). Interleukin (IL)-2, IL-6, and IL-10 mRNA were expressed in moderate to severe SS salivary gland lesions. TGF-beta mRNA was constitutively expressed in normal and SS salivary glands. In SS salivary gland cell cultures, IL-6 and IL-10 proteins were produced. TGF-beta production was reduced in high focus score SS glands. Normal and minimally involved SS salivary gland ductal epithelium and acinar cells were found to produce TGF-beta by immunostaining. In conclusion, an excess production of IL-2, IL-6, and IL-10 and a reduced production of the immunosuppressive cytokine, TGF-beta, may be responsible for the progression of the salivary gland lesion in SS. Specific immunotherapy can now be designed based on mechanisms to correct this cytokine imbalance and benefit patients with autoimmune diseases, such as SS.

Induction of transcription factors in human T lymphocytes by aspirin-like drugs

Aspirin-like drugs (ALD) induce calcium mobilization, an essential component of T cell activation, but do not induce the biosynthesis of IL-2. To understand the extent to which ALD may mimic mitogenic stimulation, we studied cytoplasmic and nuclear signaling steps in ALD-treated T cells. We found that ALD induce a transient activation of protein kinase (PKC) but have no effect (in comparison to anti-CD3 antibodies) on protein tyrosine phosphorylation nor on PCL gamma 1 tyrosine phosphorylation. ALD-induced calcium mobilization and PKC activation are independent of tyrosine protein kinase activity as shown by the lack of effect of herbimycin, a tyrosine-protein kinase-specific inhibitor. Although we detected no IL-2 mRNA in ALD-treated cells, the nuclei of these cells contain proteins capable of binding to three regulatory sequences in the IL-2 promoter region: NFAT, NF kappa B, and AP-1. These binding activities are expressed only in activated T cells. The expression of AP-1 depended on calcium mobilization and PKC activation. These data suggest that ALD cause transient but significant changes in T cell transmembrane signaling, although some events induced by stimulation with anti-CD3 antibodies are not induced by ALD. The signal is transmitted to the nucleus and induces DNA-binding activity by several transcription factors. However, the ALD stimulus is not capable of causing complete T cell activation.

Longitudinal exposure of human T lymphocytes to weak oxidative stress suppresses transmembrane and nuclear signal transduction

Products of polyamine oxidase activity, at micromolar levels and during a period of 2 to 3 days, down-regulate IL-2 mRNA levels and activity in human lymphocytes. We studied whether this suppression was associated with signal transduction abnormalities. We found that polyamine oxidase activity suppresses both anti-CD3-induced IL-2 production and protein tyrosine phosphorylation. Polyamine oxidase activity also caused a reduction in intracellular calcium mobilization after mitogenic stimulation. The most distal step of CD3-mediated signal transduction is dependent upon transcription factors that regulate a set of genes, including IL-2. We found that polyamine oxidase-treated cells exhibited very low DNA binding activity of two such factors: NFAT and NF-kappa B. On the other hand, AP-1 DNA binding activity was enhanced in polyamine oxidase-treated cells, suggesting a possible role for AP-1 in the human lymphocyte stress response. In accordance with the oxidation dependence of this suppressive mechanism, N-acetylcysteine (NAC; an antioxidant) significantly reversed the polyamine oxidase effects on lymphokine production and signal transduction. These results suggest that NAC contributes, under oxidizing conditions, to the preservation of immune function. In summary, our data suggest that chronic low-level oxidative stress, via suppression of mitogen-induced transmembrane signaling (protein-tyrosine phosphorylation and calcium mobilization), causes a decrease in the DNA binding activity of transcription factors that regulate the IL-2 gene. This results in decreased IL-2 production.

Longitudinal exposure of human T lymphocytes to weak oxidative stress suppresses transmembrane and nuclear signal transduction

Products of polyamine oxidase activity, at micromolar levels and during a period of 2 to 3 days, down-regulate IL-2 mRNA levels and activity in human lymphocytes. We studied whether this suppression was associated with signal transduction abnormalities. We found that polyamine oxidase activity suppresses both anti-CD3-induced IL-2 production and protein tyrosine phosphorylation. Polyamine oxidase activity also caused a reduction in intracellular calcium mobilization after mitogenic stimulation. The most distal step of CD3-mediated signal transduction is dependent upon transcription factors that regulate a set of genes, including IL-2. We found that polyamine oxidase-treated cells exhibited very low DNA binding activity of two such factors: NFAT and NF-kappa B. On the other hand, AP-1 DNA binding activity was enhanced in polyamine oxidase-treated cells, suggesting a possible role for AP-1 in the human lymphocyte stress response. In accordance with the oxidation dependence of this suppressive mechanism, N-acetylcysteine (NAC; an antioxidant) significantly reversed the polyamine oxidase effects on lymphokine production and signal transduction. These results suggest that NAC contributes, under oxidizing conditions, to the preservation of immune function. In summary, our data suggest that chronic low-level oxidative stress, via suppression of mitogen-induced transmembrane signaling (protein-tyrosine phosphorylation and calcium mobilization), causes a decrease in the DNA binding activity of transcription factors that regulate the IL-2 gene. This results in decreased IL-2 production.

Induction of lupus-associated autoantibodies by immunization with native and recombinant Ig polypeptides expressing a cross-reactive idiotype 4B4

A human mAb designated 4B4 with anti-Sm activity was derived from a patient with systemic lupus erythematosus. This antibody expressed a lupus-associated cross-reactive Id, partially related to the monoclonal murine anti-Sm (Y2) from MRL/lpr mice. Studies were performed to investigate the ability of 4B4 to induce lupus in nonautoimmune-prone mice. BALB/c mice immunized with 4B4 produced antibodies to dsDNA, ssDNA, Sm ribonucleoprotein, and mouse Fc fragment. There was no antibody activity against SSA/Ro, SSB/La, and hen egg lysozyme. Ag inhibition studies show that the autoantibodies were not polyreactive. Mice were also immunized with r4B4 polypeptides representing the H/L heterodimer, H chain and L chain. Autoantibodies were induced in mice immunized against the H/L and H polypeptides. No autoantibodies were induced in mice immunized with recombinant L chain. Furthermore, from 20 to 68% of antibody activity to Sm or dsDNA could be inhibited with anti-Id antiserum (either anti-4B4 or Y2). The autoantibody was initially IgM and then underwent an isotype switch to IgG. These results show that lupus-associated autoantibodies can be induced by immunization with 4B4 and that the 4B4 VH region is important in this induction process. The finding of murine IgG autoantibody expressing a cross-reactive Id similar to the immunizing 4B4 suggests a role for anti-idiotypic Th cells in this autoimmune response.

Induction of lupus-associated autoantibodies by immunization with native and recombinant Ig polypeptides expressing a cross-reactive idiotype 4B4

A human mAb designated 4B4 with anti-Sm activity was derived from a patient with systemic lupus erythematosus. This antibody expressed a lupus-associated cross-reactive Id, partially related to the monoclonal murine anti-Sm (Y2) from MRL/lpr mice. Studies were performed to investigate the ability of 4B4 to induce lupus in nonautoimmune-prone mice. BALB/c mice immunized with 4B4 produced antibodies to dsDNA, ssDNA, Sm ribonucleoprotein, and mouse Fc fragment. There was no antibody activity against SSA/Ro, SSB/La, and hen egg lysozyme. Ag inhibition studies show that the autoantibodies were not polyreactive. Mice were also immunized with r4B4 polypeptides representing the H/L heterodimer, H chain and L chain. Autoantibodies were induced in mice immunized against the H/L and H polypeptides. No autoantibodies were induced in mice immunized with recombinant L chain. Furthermore, from 20 to 68% of antibody activity to Sm or dsDNA could be inhibited with anti-Id antiserum (either anti-4B4 or Y2). The autoantibody was initially IgM and then underwent an isotype switch to IgG. These results show that lupus-associated autoantibodies can be induced by immunization with 4B4 and that the 4B4 VH region is important in this induction process. The finding of murine IgG autoantibody expressing a cross-reactive Id similar to the immunizing 4B4 suggests a role for anti-idiotypic Th cells in this autoimmune response.

Characterization of a cross-reactive idiotype on two human autoantibodies associated with systemic autoimmune disease

A human-human hybridoma was derived from a patient with primary Sjogren's Syndrome. The monoclonal antibody from this hybridoma, P36, was found to be polyreactive. P36 shared idiotypic cross-reactivity with a lupus-associated monoclonal antibody called 4B4. There was a strong correlation between P36 and 4B4 idiotype levels in systemic lupus erythematosus sera. Western blot studies showed that this shared idiotype was found on the heavy chain of both antibodies. This study shows that the heavy chain is important in the expression of this idiotype and provides another immunologic link between these two rheumatic diseases.