Bioavailability of suppository acetaminophen in healthy and hospitalized ill dogs.

To determine the plasma pharmacokinetics of suppository acetaminophen (APAP) in healthy dogs and clinically ill dogs. This prospective study used six healthy client-owned and 20 clinically ill hospitalized dogs. The healthy dogs were randomized by coin flip to receive APAP orally or as a suppository in crossover study design. Blood samples were collected up to 10 hr after APAP dosing. The hospitalized dogs were administered APAP as a suppository, and blood collected at 2 and 6 hr after dosing. Plasma samples were analyzed by ultra-performance liquid chromatography with triple quadrupole mass spectrometry. In healthy dogs, oral APAP maximal concentration (CMAX =2.69 µg/ml) was reached quickly (TMAX =1.04 hr) and eliminated rapidly (T1/2 = 1.81 hr). Suppository APAP was rapidly, but variably absorbed (CMAX =0.52 µg/ml TMAX =0.67 hr) and eliminated (T1/2  = 3.21 hr). The relative (to oral) fraction of the suppository dose absorbed was 30% (range <1%-67%). In hospitalized ill dogs, the suppository APAP mean plasma concentration at 2 hr and 6 hr was 1.317 µg/ml and 0.283 µg/ml. Nonlinear mixed-effects modeling did not identify significant covariates affecting variability and was similar to noncompartmental results. Results supported that oral and suppository acetaminophen in healthy and clinical dogs did not reach or sustain concentrations associated with efficacy. Further studies performed on different doses are needed.

Early weaning is beneficial to prevent atopic dermatitis occurrence in young children.

BACKGROUND: Epidemiological data on infant feeding practices and allergic diseases are controversial. The purpose of this study was to explore the association of early weaning with the occurrence of atopic dermatitis (AD). METHODS: We conducted a matched case-control study on incident physician-diagnosed AD in early childhood including 451 cases and 451 controls. Data on several factors, including feeding practices, were collected through an interviewer-administered questionnaire. Odds ratios (OR) and the corresponding 95% confidence intervals (CIs) were estimated through logistic regression models, conditioned on study center, age, sex, and period of interview, and adjusted for potential confounders. RESULTS: Early weaning, defined as the introduction of solid foods at 4 or 5 months of age, was inversely related to the risk of AD, with children weaned at 4 months having lower AD risk (OR = 0.41, 95% CI, 0.20-0.87) compared to those exclusively breastfed. Similar results were observed for weaning started at 5 months of age (OR = 0.39, 95% CI, 0.18-0.83). This association persisted when children with and without family history of allergy were considered separately. Prolonged partial breastfeeding (breastmilk plus milk formulas) was not associated with AD. Consistently, the introduction of a high number of different solid foods reduced the risk of AD (P trend = 0.02 at 4 months of age and P trend = 0.04 at 5 months). CONCLUSION: Our data provide evidence against the preventing role of prolonged exclusive (but not partial) breastfeeding in AD occurrence and confirm recent results indicating a beneficial role of early weaning in AD.

Quantification of circulating house dust mite-specific IL-4- and IL-13-secreting T cells correlates with rhinitis severity in asthmatic children and varies with the seasons.

BACKGROUND: Defining suitable markers to diagnose and monitor allergy and its severity is essential to correctly assign patients for specific immunotherapy. Circulating levels of specific IgE are good markers of sensitization, but not of clinically symptomatic allergy. OBJECTIVE: To quantify circulating interleukin (IL)-4- and IL-13-secreting T cells specific for house dust mite (HDM) in children presenting HDM-allergic asthma associated or not with rhinitis and correlate results with clinical symptoms. METHODS: We analysed 26 children with HDM respiratory disease (allergic rhinitis and asthma) together with six children with non-allergic asthma. Peripheral blood mononuclear cells were stimulated with HDM extract in a 24-h ELISpot assay to quantify the number of HDM-specific IL-4- and IL-13-secreting T cells. Asthma severity and control, and rhinitis severity were scored according to the Global Initiative for Asthma (GINA) and the Allergic Rhinitis and its Impact on Asthma (ARIA) Guidelines. RESULTS: The number of HDM-specific IL-4- and IL-13-secreting T cells was higher in patients with allergic asthma as compared to patients with non-allergic asthma. It varied with the season of blood sampling with two peaks in the fall and early spring. Independently of the season, the number of HDM-specific IL-4-secreting T cells correlated with rhinitis severity (OR = 2; 95% IC:1.1-3.8; P = 0.04). CONCLUSIONS AND CLINICAL RELEVANCE: Allergen-specific IL-4- and IL-13-producing T cells were only detected in HDM-allergic asthmatic children (not in patients with non-allergic asthma). Their numbers correlated with clinical severity of allergic rhinitis.

Casein-specific IL-4- and IL-13-secreting T cells: a tool to implement diagnosis of cow's milk allergy.

BACKGROUND: Cow's milk allergy (CMA) is a frequent food allergy in young children. The oral food challenge is the gold standard for diagnosis, and there is currently no reliable biological test. Our aim was to evaluate the diagnostic potential of a functional assay quantifying allergen-specific Th2 cells in CMA children. METHODS: A total of 29 children aged 2.8-10.5 years underwent a double-blind, placebo-controlled food challenge (DBPCFC) to cow's milk. Blood was collected before performing the DBPCFC, and peripheral mononuclear cells were cultured in an 18-h ELISpot assay with casein, α-lactalbumin, or ß-lactoglobulin. Numbers of antigen-specific IL-4- and IL-13-secreting lymphocytes and serum-specific IgE, IgG4, and total IgE levels were assessed. Receiver operating characteristic (ROC) curves were generated. RESULTS: A total of 17 (59%) children reacted to cow's milk and were therefore considered as allergic to cow's milk (CMA). The mean number of casein-specific IL-4- and IL-13-secreting T cells was higher in CMA than in non-CMA children (P = 0.009, 0.004, respectively). Moreover, it was inversely correlated with the cumulative dose of cow's milk tolerated (P = 0.003, 0.0009, respectively). ROC curve of combined IL-4 and IL-13 analysis showed an area under the curve of 0.98 (95% CI 0.90-1.06). For a cutoff of 10 IL-4- and 12 IL-13-secreting T cells, sensitivity and negative predictive value were 100%. CONCLUSIONS: Enumeration of casein-specific IL-4- and IL-13-secreting T cells appears a promising tool to improve diagnosis and, if confirmed in larger studies, could permit less frequent use of the oral food challenge.

Truncating mutations in CCM1, encoding KRIT1, cause hereditary cavernous angiomas.

Cavernous angiomas are vascular malformations mostly located in the central nervous system and characterized by enlarged capillary cavities without intervening brain parenchyma. Clinical symptoms include seizures, haemorrhage and focal neurological deficits. Cavernous angiomas prevalence is close to 0.5% in the general population. They may be inherited as an autosomal dominant condition in as much as 50% of cases. Cerebral cavernous malformations (CCM) loci were previously identified on 7q, 7p and 3q (refs 4,5). A strong founder effect was observed in the Hispano-American population, all families being linked to CCM1 on 7q (refs 4,7). CCM1 locus assignment was refined to a 4-cM interval bracketed by D7S2410 and D7S689 (ref. 8). Here we report a physical and transcriptional map of this interval and that CCM1, a gene whose protein product, KRIT1, interacts with RAP1A (also known as KREV1; ref. 9), a member of the RAS family of GTPases, is mutated in CCM1 families. Our data suggest the involvement of the RAP1A signal transduction pathway in vasculogenesis or angiogenesis.

Induction of allograft tolerance by monoclonal CD3 antibodies: a matter of timing.

Despite remarkable progress in organ transplantation through the development of a wealth of immunosuppressive drugs highly effective at controlling acute rejection, two major problems still remain, the loss of transplants due to chronic rejection and the growing number of sensitized recipients due to previous transplants, transfusions or pregnancies. Induction of immune tolerance appears to be the only way to curb this complex situation. Here we describe that a therapy, already successfully used to restore immune tolerance to self-antigens in overt autoimmunity, is effective at promoting transplant tolerance. We demonstrate that a short low-dose course with CD3 antibodies started after transplantation, at the time of effector T cell priming to alloantigens, induces permanent acceptance of fully mismatched islet allografts. Mechanistic studies revealed that antigen-specific regulatory and effector T cells are differentially affected by the treatment. CD3 antibody treatment preferentially induces apoptosis of activated alloreactive T cells which is mandatory for tolerance induction. In contrast, regulatory T cells are relatively spared from CD3 antibody-induced depletion and can transfer antigen-specific tolerance thus arguing for their prominent role in sustaining long-term graft survival.

Activation of natural killer T cells by alpha-galactosylceramide treatment prevents the onset and recurrence of autoimmune Type 1 diabetes.

Type 1 diabetes (T1D) in non-obese diabetic (NOD) mice may be favored by immune dysregulation leading to the hyporesponsiveness of regulatory T cells and activation of effector T-helper type 1 (Th1) cells. The immunoregulatory activity of natural killer T (NKT) cells is well documented, and both interleukin (IL)-4 and IL-10 secreted by NKT cells have important roles in mediating this activity. NKT cells are less frequent and display deficient IL-4 responses in both NOD mice and individuals at risk for T1D (ref. 8), and this deficiency may lead to T1D (refs. 1,6-9). Thus, given that NKT cells respond to the alpha-galactosylceramide (alpha-GalCer) glycolipid in a CD1d-restricted manner by secretion of Th2 cytokines, we reasoned that activation of NKT cells by alpha-GalCer might prevent the onset and/or recurrence of T1D. Here we show that alpha-GalCer treatment, even when initiated after the onset of insulitis, protects female NOD mice from T1D and prolongs the survival of pancreatic islets transplanted into newly diabetic NOD mice. In addition, when administered after the onset of insulitis, alpha-GalCer and IL-7 displayed synergistic effects, possibly via the ability of IL-7 to render NKT cells fully responsive to alpha-GalCer. Protection from T1D by alpha-GalCer was associated with the suppression of both T- and B-cell autoimmunity to islet beta cells and with a polarized Th2-like response in spleen and pancreas of these mice. These findings raise the possibility that alpha-GalCer treatment might be used therapeutically to prevent the onset and recurrence of human T1D.

Pancreatic islet beta cells drive T cell-immune responses in the nonobese diabetic mouse model.

The role of autoantigens and that of target organs in which tissue lesions develop remains elusive in most spontaneous models of autoimmune diseases. Whether the presence of target autoantigens is required for the recruitment of autoreactive lymphocytes is unknown in most cases. To evaluate the importance of islet cells in the development of autoimmunity in the nonobese diabetic (NOD) mouse, we generated beta cell-deprived mice by injecting a high dose of alloxan, a toxic agent specific for beta cells. In contrast with spleen cells from 6-mo-old naive NOD mice which transfer diabetes in irradiated 8-mo-old male recipients, spleen cells from age-matched NOD mice which received a single injection of alloxan at 3 wk of age did not transfer diabetes. With the exception of the ability to transfer diabetes, beta cell-deprived NOD mice showed maintained immune competence. Furthermore, sialitis developed with the expected intensity and prevalence in beta cell-deprived mice. Already committed "diabetogenic" spleen cells collected from spontaneously diabetic mice also showed a reduced capacity to transfer diabetes after their removal from the diabetic mice and transient "parking" in beta cell-deprived mice. Taken together, our data bring evidence that involvement of autoreactive T cells detected by the capacity to transfer diabetes requires the presence of target beta cells.

Thymic hormone-containing cells. Characterization and localization of serum thymic factor in young mouse thymus studied by monoclonal antibodies.

The characterization and distribution of cells containing the serum thymic factor (FTS) in the thymus of young mice was studied by immunofluorescence using monoclonal anti-FTS antibodies. FTS+ cells were distributed throughout the thymic parenchyma but were more frequent in the medullary region than in the cortex. FTS-containing cells presented a stellate or globular aspect, and some of them exhibited fluorescent cytoplasmic granules. The epithelial nature of FTS+ cells was confirmed by double-labeling experiments using an anti-keratin antiserum (as an epithelial cell marker). Nevertheless, only a minority of keratin-positive epithelial reticular cells contained FTS. All controls, including the incubation of sections from nonthymic tissues with the anti-FTS antibodies, were negative. Taken together, these results confirm the exclusive localization of FTS-containing cells within the mouse thymus.

Syngeneic transfer of autoimmune diabetes from diabetic NOD mice to healthy neonates. Requirement for both L3T4+ and Lyt-2+ T cells.

We have developed a model of syngeneic adoptive transfer for type I diabetes mellitus of NOD mice. This model consists in injecting spleen cells from diabetic adult mice into newborn NOD recipients. 50% of recipients inoculated with 20 X 10(6) cells develop diabetes within the first 10 wk of life, at a time when none of the control littermates have yet become diabetic. The earliest successful transfers are observed at 3 wk of age, at a time when controls do not even exhibit histological changes in their pancreas. In addition we have shown that: (a) both males and females can be adoptively transferred, despite the fact that males rarely develop spontaneous diabetes in our colony; (b) diabetes transfer is a dose-dependent phenomenon that provides an in vivo assay for comparing the autoimmune potential of spleen cells from mice at various stages of their natural history; (c) the susceptibility of the recipients to the transfer is limited in time and declines after 3 wk; and (d) both L3T4+ and Lyt-2+ T cell subsets are necessary for the successful transfer. The neonatal syngeneic transfer provides an effective model for studies of the cellular events involved at regulatory and effector stages of autoimmune type I diabetes.

T cell-mediated inhibition of the transfer of autoimmune diabetes in NOD mice.

The nonobese diabetic (NOD) mouse has recently been introduced as a model for insulin-dependent diabetes mellitus. The role of regulatory T cells in the development of antipancreatic autoimmunity in this model remains unclear. To evaluate the presence of suppressive phenomena, we used disease transfer by spleen cells from diabetic NOD mice into preirradiated adult recipients as a model for accelerated disease. Suppressor phenomena were detected by testing the protection afforded by lymphoid cells from nondiabetic NOD mice against diabetes transfer in irradiated recipients. Transfer of diabetes was delayed by reconstituting recipients with spleen cells from nondiabetic NOD donors. The greatest protection against diabetes transfer was conferred by spleen cells from 8-wk-old nondiabetic female NOD mice. Depletion experiments showed that the protection was dependent on CD4+ cells. Protection was also detected within thymic cells from nondiabetic NOD mice and protection conferred by spleen cells was abrogated by thymectomy of nondiabetic female, but not male, NOD donors at 3 wk of age. These findings indicate that suppressive CD4+ T cells that are dependent on the presence of the thymus may delay the onset of diabetes in female diabetes-prone NOD mice.

Overexpression of natural killer T cells protects Valpha14- Jalpha281 transgenic nonobese diabetic mice against diabetes.

Progression to destructive insulitis in nonobese diabetic (NOD) mice is linked to the failure of regulatory cells, possibly involving T helper type 2 (Th2) cells. Natural killer (NK) T cells might be involved in diabetes, given their deficiency in NOD mice and the prevention of diabetes by adoptive transfer of alpha/beta double-negative thymocytes. Here, we evaluated the role of NK T cells in diabetes by using transgenic NOD mice expressing the T cell antigen receptor (TCR) alpha chain Valpha14-Jalpha281 characteristic of NK T cells. Precise identification of NK1.1(+) T cells was based on out-cross with congenic NK1.1 NOD mice. All six transgenic lines showed, to various degrees, elevated numbers of NK1.1(+) T cells, enhanced production of interleukin (IL)-4, and increased levels of serum immunoglobulin E. Only the transgenic lines with the largest numbers of NK T cells and the most vigorous burst of IL-4 production were protected from diabetes. Transfer and cotransfer experiments with transgenic splenocytes demonstrated that Valpha14-Jalpha281 transgenic NOD mice, although protected from overt diabetes, developed a diabetogenic T cell repertoire, and that NK T cells actively inhibited the pathogenic action of T cells. These results indicate that the number of NK T cells strongly influences the development of diabetes.

The peptide-binding motif for the human transporter associated with antigen processing.

Presentation of antigenic peptides by human leukocyte antigen class I molecules is dependent on peptide transport into the endoplasmic reticulum by the transporters associated with antigen processing (TAP) (Germain, R. N. 1994. Cell. 76:287-299). This translocation step is currently regarded as permissive for all peptides with COOH-terminal residues capable of binding to HLA class I molecules (Momburg, F., J. Roelse, J. C. Howard, G. W. Butcher, G.J. Hämmerling, and J.J. Neefjes. 1994. Nature (Lond.). 367:648-651). In this report, we show that the human transporter selects peptides according to a binding motif based on the strong effects on peptide affinity of the three NH2-terminal positions and the COOH-terminal residues. TAP favors strongly hydrophobic residues in position 3 (P3) and hydrophobic or charged residues in P2, whereas aromatic or acidic residues in P1, as well as Pro in P1 and P2, have strong deleterious effects. Selection of naturally presented peptides by the transporter is suggested by their higher average affinity for TAP, as compared to nonselected peptides. The TAP preferences in the three NH2-terminal positions correspond to those of the vast majority of human leukocyte antigen class I alleles, but they represent an obstacle for peptide supply to some alleles, e.g., the B7-like group. We propose that peptides binding to these alleles, and in general, peptides with TAP affinities below a certain threshold, may be transported as extended precursors.

The 'hygiene hypothesis' for autoimmune and allergic diseases: an update.

According to the 'hygiene hypothesis', the decreasing incidence of infections in western countries and more recently in developing countries is at the origin of the increasing incidence of both autoimmune and allergic diseases. The hygiene hypothesis is based upon epidemiological data, particularly migration studies, showing that subjects migrating from a low-incidence to a high-incidence country acquire the immune disorders with a high incidence at the first generation. However, these data and others showing a correlation between high disease incidence and high socio-economic level do not prove a causal link between infections and immune disorders. Proof of principle of the hygiene hypothesis is brought by animal models and to a lesser degree by intervention trials in humans. Underlying mechanisms are multiple and complex. They include decreased consumption of homeostatic factors and immunoregulation, involving various regulatory T cell subsets and Toll-like receptor stimulation. These mechanisms could originate, to some extent, from changes in microbiota caused by changes in lifestyle, particularly in inflammatory bowel diseases. Taken together, these data open new therapeutic perspectives in the prevention of autoimmune and allergic diseases.

99th Dahlem conference on infection, inflammation and chronic inflammatory disorders: immune therapies of type 1 diabetes: new opportunities based on the hygiene hypothesis.

Insulin-dependent (type 1) diabetes is a prototypic organ-specific autoimmune disease resulting from the selective destruction of insulin-secreting beta cells within pancreatic islets of Langerhans by an immune-mediated inflammation involving autoreactive CD4(+) and CD8(+) T lymphocytes which infiltrate pancreatic islets. Current treatment is substitutive, i.e. chronic use of exogenous insulin which, in spite of significant advances, is still associated with major constraints (multiple daily injections, risks of hypoglycaemia) and lack of effectiveness over the long term in preventing severe degenerative complications. Finding a cure for autoimmune diabetes by establishing effective immune-based therapies is a real medical health challenge, as the disease incidence increases steadily in industrialized countries. As the disease affects mainly children and young adults, any candidate immune therapy must therefore be safe and avoid a sustained depression of immune responses with the attendant problems of recurrent infection and drug toxicity. Thus, inducing or restoring immune tolerance to target autoantigens, controlling the pathogenic response while preserving the host reactivity to exogenous/unrelated antigens, appears to be the ideal approach. Our objective is to review the major progress accomplished over the last 20 years towards that aim. In addition, we would like to present another interesting possibility to access new preventive strategies based on the 'hygiene hypothesis', which proposes a causal link between the increasing incidence of autoimmune diseases, including diabetes, and the decrease of the infectious burden. The underlying rationale is to identify microbial-derived compounds mediating the protective activity of infections which could be developed therapeutically.

Ultrastructural study of spontaneous bone marrow rosette-forming cells.

Mouse bone marrow contains spontaneous rosette-forming cells (RFC) which include more than 70% T-cell precursors, as assessed by their transformation into theta-positive cells after incubation with thymic hormone. Such spontaneous RFC, examined in C57B1/6 mouse bone marrow by electron and scanning electron microscopy, have consistently been shown to be small, inactive mouse lymphocytes when macrophages have been eliminated by cell preincubation. These data suggest that thymic hormone target cells include small quiescent lymphocytes.

The human immune response to the OKT3 monoclonal antibody is oligoclonal.

The availability of highly specific and homogeneous antibodies to human T cells by the hybridoma technique has elicited new interest in the clinical use of antibodies to lymphocytes as immunosuppressive agents. OKT3 is the murine monoclonal antibody that has been the most widely used in clinical transplantation to induce immunosuppression. This antibody recognizes a membrane molecular complex, exclusively present on mature human T lymphocytes, which is tightly linked to the T-cell antigen receptor. The long-term therapeutic use of murine monoclonal antibodies in vivo is hampered by the intense antibody response that occurs in most human patients. Thus, when administered alone, OKT3 manifests its immunosuppressive activity only during the 10 to 15 days that precede the onset of sensitization. The results presented here show, by use of isoelectrofocusing, that the antibody response to OKT3, already reported to be restricted in its specificity (only anti-isotypic and anti-idiotypic antibodies are produced), is in addition oligoclonal. This restriction of the anti-monoclonal response may suggest that an efficient way to circumvent the sensitization problem would be to administer consecutively different monoclonal antibodies presenting the same specificity but distinct idiotypes.