Biomedical subjects

R A Daynes

Publications and source records attributed to R A Daynes.

At least 19 recordsLinked to original sources

PubMed2001

CpG DNA functions as an effective adjuvant for the induction of immune responses in aged mice.

The present studies demonstrate that the immunization of aged mice with Diphtheria toxoid in formulations containing unmethylated immunostimulatory CpG motifs, promotes the successful development of immune responses that are qualitatively and quantitatively comparable to those induced in young animals vaccinated in a similar manner. Aged mice given vaccines containing CpG oligodeoxynucleotides (ODNs) expressed primary and secondary systemic humoral immune responses having isotype profiles consistent with an enhancement in Th-1 type immunity. The ability to generate common mucosal immunity was also restored in aged animals given CpG ODN-containing vaccines. Dendritic cells (DCs) were determined to represent one of the cellular targets of CpG ODN activities in aged mice since restoration of immune function was observed when DCs from aged donors were pulsed with antigen and CpG ODNs, prior to injection into syngeneic young adult or aged recipients. Interestingly, antigen-pulsed DCs from young donors were fully capable of stimulating immune responses following their injection into syngeneic young adult or aged hosts, without a need for exposure to CpG ODNs. Although the mechanism(s) by which CpG DNA exerts its beneficial adjuvant effects on the aged immune system remains unclear, our findings suggest that the incorporation of CpG ODNs into vaccine formulations provided to the aged could prove useful in the development of more effective vaccines for the elderly.

Adjuvants, Immunologic↗

PubMed2001

Salmonella DNA adenine methylase mutants confer cross-protective immunity.

Salmonella isolates that lack or overproduce DNA adenine methylase (Dam) elicited a cross-protective immune response to different Salmonella serovars. The protection afforded by the Salmonella enterica serovar Typhimurium Dam vaccine was greater than that elicited in mice that survived a virulent infection. S. enterica serovar Typhimurium Dam mutant strains exhibited enhanced sensitivity to mediators of innate immunity such as antimicrobial peptides, bile salts, and hydrogen peroxide. Also, S. enterica serovar Typhimurium Dam(-) vaccines were not immunosuppressive; unlike wild-type vaccines, they failed to induce increased nitric oxide levels and permitted a subsequent robust humoral response to diptheria toxoid antigen in infected mice. Dam mutant strains exhibited a low-grade persistence which, coupled with the nonimmunosuppression and the ectopic protein expression caused by altered levels of Dam, may provide an expanded source of potential antigens in vaccinated hosts.

Animals↗

PubMed2000

The induction of systemic and mucosal immune responses to antigen-adjuvant compositions administered into the skin: alterations in the migratory properties of dendritic cells appears to be important for stimulating mucosal immunity.

The properties of various vaccine-adjuvant formulations that are capable of inducing both systemic and common mucosal immunity subsequent to their intradermal administration are described. Effective mucosal adjuvants, including bacterial toxins, chemical enhancers of cyclic AMP, and the active form of vitamin D3, all shared the ability to promote dendritic cell migration from the skin to Peyer's patches subsequent to antigen induced maturation. Our data suggests that skin dendritic cells may function as effective antigen presenting cells for the induction of mucosal immune responses, if microenvironmental conditions are appropriately manipulated subsequent to their stimulation by antigen.

Administration, Topical↗

PubMed2000

Enhancement of common mucosal immunity in aged mice following their supplementation with various antioxidants.

Common mucosal immune responses were depressed in aged mice that were orally immunized with Haemophilus influenzae type b oligosaccharide conjugated to Diphtheria CRM197 protein (Hib-DT) vaccine using cholera toxin as the mucosal adjuvant. Both common mucosal and systemic humoral immune responses were also depressed in aged mice that were subcutaneously immunized with vaccine formulations containing Hib-DT plus 1alpha,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)). Dietary supplementation of aged mice with either the antioxidant vitamin E, or with known activators of the alpha isoform of the peroxisome proliferator activated receptor (PPAR-alpha) was capable of restoring their mucosal and systemic humoral immune responses to mature adult levels, by both the oral and subcutaneous routes of immunization. These data support a hypothesis that some aspects of immunosenescence are due to dysregulations in cellular functions, and are not due to any irreversible defects in cellular components of the immune system.

Aging↗

PubMed2000

Ganglioside control over IL-4 priming and cytokine production in activated T cells.

Our previous studies have shown that the enzymatic activities of Neu-1, an endogenous sialidase encoded in the murine MHC, are involved in promoting IL-4 synthesis by naive CD4(+)T cells. Our present studies have characterized responsible sialoconjugate targets of Neu-1 and questioned possible biochemical mechanisms responsible for their regulatory influences on IL-4 gene expression. These studies determined that treatment of T cells with the naturally occurring ganglioside GM3 inhibited the production of IL-4 without affecting the production of IL-2. An analysis of IL-4-primed CD4(+)T cells further demonstrated that GM3 treatment specifically inhibited the restimulated production of IL-4, IL-5 and IL-13, without inhibiting the production of IL-2 and IFN-gamma. The inhibitory effects of GM3 could be overcome by treatment with thapsigargin or ionomycin, suggesting ganglioside regulation occurs upstream of activation-induced calcium mobilization. GM3 treatment attenuated the level of calcium influx following CD3epsilon crosslinking, and CD4(+)T cells from Neu-1-deficient B10.SM strain mice (neu-1(a)and IL-4-deficient) expressed reduced levels of intracellular calcium following activation. Our results indicate that activities by membrane gangliosides can influence the cytokine programs in CD4(+)T cells, possibly through the modulation of calcium responses induced by T cell activation.

Animals↗

PubMed1999

The induction of systemic and mucosal immune responses following the subcutaneous immunization of mature adult mice: characterization of the antibodies in mucosal secretions of animals immunized with antigen formulations containing a vitamin D3 adjuvant.

Systemic and mucosal immune responses were effectively induced following the subcutaneous administration of Haemophilus influenzae type b oligosaccharide conjugated to diphtheria toxoid vaccine in a formulation containing the active form of vitamin D3. IgA and IgG antibodies with specificity for both the protein and oligosaccharide components of the vaccine were detectable in mucosal secretions following immunization. The IgA and IgG mucosal antibodies were produced locally, and were functional as demonstrated by their diphtheria toxin neutralizing activity. Our data suggests that subcutaneous tissues can effectively serve as effective antigen presenting sites for both mucosal and systemic immune responses to antigens administered in combination with vitamin D3.

Adjuvants, Immunologic↗

PubMed1999

Age-associated alterations in splenic iNOS regulation: influence of constitutively expressed IFN-gamma and correction following supplementation with PPARalpha activators or vitamin E.

Alterations in transcription factor activities in aged mice may lead to the production of many inflammatory molecules in the absence of exogenous stimulation. Splenocytes from 22-month-old female C57BL/6 mice are dysregulated in their capacity to control the inducible nitric oxide synthase gene as a result of elevations in the endogenous levels and activity of interferon (IFN)-gamma. Splenocytes from aged mice produced high levels of IFN-gamma in vitro and active STAT-1 was found in nuclear extracts from these splenocytes. Administration to aged mice of neutralizing antibodies against IFN-gamma imposed appropriate regulation over nitric oxide production by stimulated splenocytes. Reestablishment of normal redox balance following dietary supplementation of aged mice with activators of the peroxisome proliferator-activated receptor alpha or the antioxidant alpha-tocopherol (vitamin E) restored appropriate regulation over both the production of IFN-gamma and the secretion of nitric oxide.

Aging↗

PubMed1999

Correlation of serum L-carnitine and dehydro-epiandrosterone sulphate levels with age and sex in healthy adults.

OBJECTIVES: L-carnitine and dehydro-epiandrosterone (DHEA) independently promote mitochondrial energy metabolism. We therefore wondered if an age-related deficiency of L-carnitine or DHEA may account for the declining energy metabolism associated with age. METHODS: we evaluated serum levels of L-carnitine and the sulphated derivative of DHEA (DHEAS) in cross-sectional study of 216 healthy adults, aged 20-95. RESULTS: serum DHEAS levels declined, while total carnitine levels increased with age (P < 0.0001). Total and free carnitine and DHEAS levels were lower in women than men (P < 0.0001). Esterified/free (E/F) carnitine (inversely related to carnitine availability) increased with age in both sexes (P=0.012). CONCLUSION: reduced carnitine availability correlates with the age-related decline of DHEAS levels. These results are consistent with the hypothesis that decreased energy metabolism with age relates to DHEAS levels and carnitine availability.

Adult↗

PubMed1998

Peroxisome proliferator-activated receptor alpha activation modulates cellular redox status, represses nuclear factor-kappaB signaling, and reduces inflammatory cytokine production in aging.

In aged mice, the redox-regulated transcription factor nuclear factor-kappaB (NF-kappaB) becomes constitutively active in many tissues, as well as in cells of the hematopoietic system. This oxidative stress-induced activity promotes the production of a number of pro-inflammatory cytokines, which can contribute to the pathology of many disease states associated with aging. The administration to aged mice of agents capable of activating the alpha isoform of the peroxisome proliferator-activated receptor (PPARalpha) was found to restore the cellular redox balance, evidenced by a lowering of tissue lipid peroxidation, an elimination of constitutively active NF-kappaB, and a loss in spontaneous inflammatory cytokine production. Aged animals bearing a null mutation in PPARalpha failed to elicit these changes following treatment with PPARalpha activators, but remained responsive to vitamin E supplementation. Aged C57BL/6 mice were found to express reduced transcript levels of PPARalpha and the peroxisome-associated genes acyl-CoA oxidase and catalase. Supplementation of these aged mice with PPARalpha activators or with vitamin E caused elevations in these transcripts to levels seen in young animals. Our results suggest that PPARalpha and the genes under its control play a role in the evolution of oxidative stress excesses observed in aging.

Acyl-CoA Oxidase↗

PubMed1998

Inhibition of skin 11beta-hydroxysteroid dehydrogenase activity in vivo potentiates the anti-inflammatory actions of glucocorticoids.

Synthetic forms of glucocorticoids (GCs) with high potency are widely used to treat a number of dermatological conditions having an inflammatory or autoimmune etiology. While GCs are generally effective in their ability to suppress inflammatory processes, their chronic use can lead to detrimental systemic side effects. In this report, we describe a method by which the localized antiinflammatory potential of the natural GC cortisol can be significantly augmented without increasing the risk of negative systemic effects. 11Beta-hydroxysteroid dehydrogenase (11beta-HSD) is a naturally occurring enzyme in the skin. 11Beta-HSD functionally converts biologically active 11-hydroxy GCs to their biologically inactive 11-keto metabolites, thereby limiting the ability of GCs to mediate antiinflammatory activities. By topically applying specific inhibitors of 11beta-HSD in conjunction with low doses of GCs, the antiinflammatory properties of cortisol can be significantly potentiated. It was observed that the generation of the effector phase of contact hypersensitivity (CH) responses could be suppressed by this combined treatment under conditions where the 11beta-HSD inhibitor alone, or cortisol alone were only minimally effective. Only the combined treatment was effective at inhibiting the progression of an ongoing CH response.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1997

Activation of NK1.1+ T cells in vitro and their possible role in age-associated changes in inducible IL-4 production.

Interleukin (IL)-12 or IL-4 produced early in an immune response directs the differentiation of naive antigen-activated CD4+ T cells down a Th1 or Th2 pathway. The NK1.1+ subset of T cells promptly produces IL-4 following activation in vivo. We demonstrate here that NK1.1+ T cells can be directly induced to produce IL-4 in vitro when activated under serum-free culture conditions. Platelet-derived growth factor in cell culture medium was inhibitory to the production of IL-4 by NK1.1+ T cells in vitro. Lymphocytes obtained from secondary lymphoid organs of aged mice produced greater quantities of IL-4 following stimulation than lymphocytes from mature adult animals. Aged mice expressed elevated percentages of NK1.1+ T cells in their secondary lymphoid organs and peripheral blood. While this cell type was responsible for the total early IL-4 produced by lymphocytes from mature adult mice, both NK1.1+ and memory phenotype (CD44high, CD45RBlow, NK1.1-) T cells from aged donors produced IL-4 following polyclonal T cell activation.

Actins↗

PubMed1997

The control of IL-4 gene expression in activated murine T lymphocytes: a novel role for neu-1 sialidase.

IL-4 is important in controlling the development of immune responses. Following activation with anti-CD3epsilon under serum-free conditions, splenocytes from most normal (neu-1b) mouse strains directly produced IL-4 and other T cell cytokines. However, splenic T cells from SM/J and B10.SM (H-2v, neu-1a) strain mice, deficient in neu-1 sialidase activity, failed to produce IL-4 but produced normal levels of IL-2 following activation. Moreover, sialidase-deficient mice produced markedly less IgE and IgG1 Abs following immunization with protein Ags than did mouse strains with normal neu-1 sialidase activity. Enriched T cells from neu-1a mice failed to be effectively primed with exogenous murine IL-4 to become IL-4-producing cells. Treatment of splenocytes or enriched T cells from neu-1a mice with bacterial sialidase prior to activation or IL-4 priming promoted their subsequent capacity to produce IL-4. In contrast, activation of T cells from neu-1b mice in the presence of a sialidase inhibitor almost completely blocked subsequent IL-4 production. The presence of IL-4 during priming enhanced T cell expression of neu-1-specific sialidase activity and increased the membrane expression of asialo-G(M1) compared with T cells activated without IL-4. These results suggest that T cell-associated neu-1 sialidase is required for early IL-4 production by splenic T cells and is involved in the IL-4 priming process of conventional T cells to become active IL-4 producers.

Animals↗

PubMed1997

Active catabolism of glucocorticoids by 11 beta-hydroxysteroid dehydrogenase in vivo is a necessary requirement for natural resistance to infection with Listeria monocytogenes.

The results from the present study demonstrate that the innate defense mechanisms which control the progressive growth of Listeria monocytogenes in normal animals in vivo are dependent upon the active catabolism of endogenous glucocorticoids by the enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD). When 11 beta-HSD activity was pharmacologically inhibited in vivo, host susceptibility to progressive bacterial disease was markedly increased. Depressed natural resistance following 11 beta-HSD inhibition correlated with changes in the patterns of inducible cytokines by macrophages and T cells. Similar changes were observed when normal adult animals were treated with low doses of dexamethasone prior to experimental infection with Listeria.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1997

Constitutive activation of NF-kappa B in an animal model of aging.

The pathophysiology of many disease states observed in aged individuals has been linked to the dysregulated production of several pleiotropic cytokines. We have demonstrated that NF-kappa B, a major transcriptional regulator of these aberrantly expressed cytokines, exists in a constitutively activated state in cells obtained from the major lymphoid organs of aged animals. Therapeutic treatment with dietary antioxidants or with agents capable of activating the peroxisome proliferator-activated receptor (PPAR)-alpha was able to correct the abnormal nuclear NF-kappa B activity, reduce lipid peroxide levels, and eliminate the dysregulated expression of cytokines and other genes under NF-kappa B control. These results suggest that abnormal activation of NF-kappa B in aging contributes to the dysregulated expression of certain pleiotropic cytokines. Effective therapeutic regimens for aging and other inflammatory disease states might benefit from the administration of antioxidants or other agents which specifically activate PPAR-alpha.

Aging↗

PubMed1997

IL-12 directly stimulates expression of IL-10 by CD5+ B cells and IL-6 by both CD5+ and CD5- B cells: possible involvement in age-associated cytokine dysregulation.

Constitutive expression of p35 and p40 IL-12 mRNA was detected in splenic macrophages isolated from aged mice. Macrophages were also implicated as the cell type responsible for the dysregulated IL-6 and tumor necrosis factor (TNF)-alpha commonly observed to be constitutively produced by lymphoid cells from aged donors. A role for IL-12 in the aging process was suggested when it was found that recombinant IL-12 (rIL-12) directly stimulated splenic CD5+ B cells to secrete IL-10, and both CD5+ and CD5- B cells could be directly induced to produce IL-6 in response to rIL-12. Furthermore, splenocytes from aged animals cultured in the presence of anti-IL-12 antibodies demonstrated a significant reduction in spontaneous IL-6, IL-10 and IFN-gamma production. Based on these observations it was concluded that IL-12 might be responsible for the dysregulated production of IL-10 and IFN-gamma known to occur in aged animals. Treatment of aged animals with low doses of dehydroepiandrosterone sulfate, previously established to be immunocorrective in immunosenescent animals, reduced the age-associated alterations in IL-12 mRNA and protein expression. The mechanisms responsible for the abnormal constitutive expression of inflammatory cytokines by the macrophages of aged animals may play an important afferent role in establishing the immunosenescent phenotype.

Aging↗

PubMed1996

The use of oral dehydroepiandrosterone sulfate as an adjuvant in tetanus and influenza vaccination of the elderly.

Elderly individuals often exhibit a poorer immune response and shorter duration of immunity to vaccines than younger persons. Improvement in vaccine response has been demonstrated when administering the hormone dehydroepiandrosterone sulfate (DHEAS) as an adjuvant in animal trials. Two separate, randomized double-blinded vaccine trials were therefore conducted using DHEAS as an oral adjuvant in individuals age 65 or older. Sixty-six individuals were randomized to DHEAS, 50 mg po bid for 4 days, or a placebo capsule. Tetanus vaccination was given immediately before the fifth dose. At entry the level of protective antibody was age-dependent (P = 0.009), and by 28 days post-vaccination most individuals had protective levels of antibody, with no difference noted between treatment groups. In the second study, 67 individuals received placebo capsules or DHEAS immediately before and 24 h after influenza vaccination. The number of individuals who developed protective titers (> or = 1:40) was not different in the two groups. The mean log increase in HAI response was greater in the DHEAS group to all three vaccine components, although this did not achieve significance. Minimal side-effects of DHEAS administration were noted. Given the trend toward improved response in the elderly to influenza, larger trials using DHEA as an adjuvant in vaccines that are neoantigens may be indicated.

Adjuvants, Immunologic↗

PubMed1996

Nucleic acid vaccine encoding gD2 protects mice from herpes simplex virus type 2 disease.

Nucleic acid vaccinations with plasmids pWW65, containing the sequence for herpes simplex type 2 (HSV-2) gD2, and pRSVnt, lacking the gD sequence, were studied. Groups of mice were immunized with pWW65 alone, pWW65 plus 1,25-dihydroxyvitamin-D3 (D3), or pRSVnt. Clinical disease (vaginitis), serum and vaginal washing antibody levels, and vaginal washing virus titers were measured intravaginal HSV-2 challenge. No animals (0/10) in the pWW65 + D3 group, 6/10 animals in the pWW65 group, and 10/10 animals in the pRSVnt group developed severe disease by postchallenge day 13 (P<.001, P=.04 vs. pRSVnt). Virus titers in vaginal washings were significantly reduced in the pWW65 and pWW65+D3 groups versus the pRSVnt group (P<.001). Increasing levels of serum anti-gD2 antibodies were measured 2 and 6 days after challenge among animals in the pWW65 and pWW65+D3 groups but not among animals in the pRSVnt group. Vaccinations with a plasmid containing the gD2 gene are immunogenic and provide some protection from HSV-2-induced disease.

Animals↗

PubMed1996

Induction of common mucosal immunity by hormonally immunomodulated peripheral immunization.

The study described in this report demonstrates that peripheral lymph nodes draining nonmucosal tissues can effectively serve as induction sites for the establishment of common mucosal immunity if the microenvironmental conditions are altered to mimic those normally present within mucosa-associated lymphoid tissues (e.g., Peyer's patches). Lymph node lymphocytes exposed in situ to the immunomodulatory influences of the hormone 1 alpha, 25-dihydroxy vitamin D 3 were found to produce less gamma interferon and interleukin-2 (IL-2) and far more IL-4, IL-5 and IL-10 than lymphocytes from control animals. When couples with vaccination with hepatitis B surface antigen (HBsAg), the hormone, immunomodulated switch from a peripheral lymph node phenotype to a Peyer's patch-like pattern promoted the induction of both a systemic and a common mucosal immune response. This was determined by the observed increased concentrations of serum anti-HBsAg antibody and by finding that anti-HBsAg secretory antibodies were detectable in urogenital, lachrymal, fecal and oral secretions only in the hormone-treated animals. In addition, specific antibody-secreting cells were detectable in the lamina propria of the lungs and small intestines of the hormone-treated animals subsequent to vaccination, indicating that the homing properties of antigen-specific B cells were being affected by the treatment procedure. The humoral and mucosal immune responses were further augmented if both 1 alpha, 25-dihydroxy vitamin D 3 and dehydroepiandrosterone were used together as hormonal immunomodulators. This novel immunization technique may afford new opportunities to effectively intervene in sexually transmitted diseases and other diseases caused by mucosal pathogens.

Adjuvants, Immunologic↗