Methodologies for developmental immunotoxicity (DIT) testing

Developmental immunotoxicity has gained increasing recognition as a significant factor influencing the risk of later life disease. Based on the data collected thus far on different chemicals and drugs, the developing immune system can be significantly more sensitive than the adult immune system to xenobiotic-induced insult. There are distinct differences between the immune system surrounding birth and that in the mature adult as well as differences in the nature of immunotoxic changes based on age. Immunosuppresssion is not the only concern. Immunotoxic changes that increase the risk for allergic or autoimmune responses should also be considered. Therefore, one should not assume that immunotoxicity assays validated for adult exposure assessment are inherently the most predictive for developmental immunotoxicology (DIT) evaluation. Many of those adult-based protocols were developed solely to detect immunosuppression, whereas DIT concerns include shifts in immune balance. For this reason, it is useful to examine the various immune endpoints that have been employed in recent perinatal immunotoxicity studies, compare those against routine adult immunotoxicity evaluation protocols, and consider the options that are available for effective DIT testing. The results published on several chemicals and drugs in recent years suggest that functional tests are a front-line priority for perinatal immunotoxicity detection and that a combination of at least two functional tests (such as a multi-isotype T-dependent antibody response (TDARs), and a cell-mediated immune response assay such as the delayed-type hypersensitivity assay and/or T cell or NK cytotoxicity assays) should be paired with immune cell populations and histopathological analysis. Cytokine production measurements offer outstanding promise and may eventually be able to be substituted for other more laborious procedures. However, multi-cytokine analysis needs to be standardized in terms of optimum source for analysis and protocol.

Th1 and type 1 cytotoxic T cells dominate responses in T-bet overexpression transgenic mice that develop contact dermatitis

Contact dermatitis in humans and contact hypersensitivity (CHS) in animal models are delayed-type hypersensitivity reactions mediated by hapten-specific T cells. Recently, it has become clear that both CD4(+) Th1 and CD8(+) type 1 cytotoxic T (Tc1) cells can act as effectors in CHS reactions. T-bet has been demonstrated to play an important role in Th1 and Tc1 cell differentiation, but little is known about its contribution to CHS. In the present study, we used C57BL/6 mice transgenic (Tg) for T-bet to address this issue. These Tg mice, which overexpressed T-bet in their T lymphocytes, developed dermatitis characterized by swollen, flaky, and scaly skin in regions without body hair. Skin histology showed epidermal hyperkeratosis, neutrophil, and lymphocyte infiltration similar to that seen in contact dermatitis. T-bet overexpression in Tg mice led to elevated Th1 Ig (IgG2a) and decreased Th2 Ig (IgG1) production. Intracellular cytokine analyses demonstrated that IFN-gamma was increased in both Th1 and Tc1 cells. Furthermore, Tg mice had hypersensitive responses to 2,4-dinitrofluorobenzene, which is used for CHS induction. These results suggest that the level of expression of T-bet might play an important role in the development of contact dermatitis and that these Tg mice should be a useful model for contact dermatitis.

A human mAb specific to oncofetal fibronectin selectively targets chronic skin inflammation in vivo

The antibody-based targeted delivery of bioactive agents to sites of angiogenesis is an attractive therapeutic strategy for cancer treatment, but is largely unexplored for chronic inflammatory diseases. In this article, we show that the extra domain B (EDB) domain of fibronectin, a marker of angiogenesis, is expressed in psoriatic lesions, and that the anti-EDB human antibody L19 can selectively localize to chronically inflamed skin in vivo. The L19-based delivery of the cytokines IL10 and IL12 did not improve or worsen inflammation in a mouse model of chronic skin inflammation, which overexpressed vascular endothelial growth factor under the control of the keratin-14 promoter. By contrast, the L19-based targeted delivery of the proinflammatory cytokine IL2 or of the photosensitizer Sn(IV) chlorin e6 resulted in an increased swelling and reddening of inflamed skin. These results indicate that antibodies specific to components of the modified extracellular matrix can selectively accumulate at chronically inflamed sites in vivo. This observation now stimulates the search for bioactive molecules which can be fused to antibodies and which may confer a therapeutic benefit as a result of their preferential accumulation in psoriatic lesions and other sites of inflammation.

CD3+ cells transfer the hypersensitive granulomatous response to mycobacterial glycolipid trehalose 6,6′-dimycolate in mice

The granulomatous response is the characteristic histological feature ofMycobacterium tuberculosisinfection that is essential for organism containment. Trehalose 6,6-dimycolate (TDM), a cell-wall glycolipid present on most mycobacterial species, has been implicated in the pathogenesis ofM. tuberculosisinfection. TDM has potent immunoregulatory and inflammatory properties, and can be used to model granulomatous reactions that mimic, in part, pathology caused during active infection. This study examined the hypersensitive granulomatous response, focusing on cellular responses specific to TDM. Lungs from mice immunized with TDM emulsion demonstrated exacerbated histological damage, inflammation, and lymphocytic infiltration upon subsequent challenge with TDM. Splenocytes recovered from these mice demonstrated significant interferon (IFN)-γproduction during recall response to TDM, as well as increased production of proinflammatory mediators (tumour necrosis factor-α, interleukin-6 and macrophage inflammatory protein-1α). The exacerbated response could be adoptively transferred to naïve mice. Administration of non-adherent lymphocytes or purified CD3+cells from TDM-immunized mice led to increased inflammation, lymphocytic infiltration, and vascular endothelial cell damage upon challenge with TDM. Recipient mice that received immunized CD3+lymphocytes demonstrated significant increases in Th1-type cytokines and proinflammatory mediators in lung tissue following TDM challenge. When CD1d−/−mice were immunized with TDM, they failed to generate a specific IFN-γresponse, suggesting a role for this molecule in the generation of hypersensitivity. These experiments provide further evidence for the involvement of TDM-specific CD3+T cells in pathological damage elicited duringM. tuberculosisinfection.

Delayed hypersensitivity skin testing in the Thai adult population

OBJECTIVE

The present study was carried out in healthy Thai subjects to determine the types and concentrations of standard antigens used in delayed-type hypersensitivity (DTH) skin testing as an evaluation of cell-mediated immunity.

MATERIAL AND METHOD

One hundred subjects were tested with three antigens including tuberculin (purified protein derivative), tetanus toxoid, 1:10 and 1:100 dilutions, and Candida albicans, 1:10 and 1:100 dilutions.

RESULTS

We found that 92% of the subjects responded to tuberculin and/or tetanus toxoid at a 1:10 dilution, 77% responded to tetanus toxoid at a 1:10 dilution, and 35% responded to a 1:100 dilution. There was only one subject who responded to Candida albicans at a 1:10 dilution, and none to a 1:100 dilution. The size of tuberculin reactions varied from 5 mm to over 20 mm without any evidence of active tuberculosis.

CONCLUSION

Tuberculin and tetanus toxoid at a 1:10 dilution are probably sufficient to be used in DTH skin testing to evaluate T-cell function.

Alcohol-induced gastritis prevents oral tolerance induction in mice

Despite several reports on the immunological relationship between inflammatory bowel diseases and immunoregulatory mechanisms in the gut, systematic studies addressing the impact of inflammatory processes in the gastric mucosa on events, such as oral tolerance, are still limited. Herein, we report the establishment of a novel murine model of gastritis induced by short-term administration of ethanol. The major immumological features of this clinical entity are characterized, as well as its impact on the induction of oral tolerance. Our data demonstrate that ethanol ingestion during 4 consecutive days triggered an acute inflammatory reaction in the stomach referred as ethanol-induced gastritis and characterized by hyperaemia, oedema and mixed mononuclear/polymorphonuclear cell infiltrate. Besides local immunological changes, such as high levels of gastric interleukin (IL)-4 and interferon (IFN)-gamma, systemic alterations are also observed, including increased IL-4 synthesis, enhanced levels of serum IgE and absence of IL-10 production by spleen cells. Moreover, ethanol-induced gastritis prevents oral tolerance induction to ovalbumin (OVA) as demonstrated by unaltered anti-OVA humoral and cellular immune responses in treated animals. Tissue eosinophilia after footpad immunization with OVA suggests that oral treatment with ethanol induced an allergic-type reaction. Taken together, our findings indicate that short-term ethanol ingestion is associated with gastric inflammatory events able to break immunoregulatory mechanisms that maintain mucosal homeostasis and oral tolerance.

Platelet-activating factor is crucial in psoralen and ultraviolet A-induced immune suppression, inflammation, and apoptosis

Psoralen plus UVA (PUVA) is used as a very effective treatment modality for various diseases, including psoriasis and cutaneous T-cell lymphoma. PUVA-induced immune suppression and/or apoptosis are thought to be responsible for the therapeutic action. However, the molecular mechanisms by which PUVA acts are not well understood. We have previously identified platelet-activating factor (PAF), a potent phospholipid mediator, as a crucial substance triggering ultraviolet B radiation-induced immune suppression. In this study, we used PAF receptor knockout mice, a selective PAF receptor antagonist, a COX-2 inhibitor (presumably blocking downstream effects of PAF), and PAF-like molecules to test the role of PAF receptor binding in PUVA treatment. We found that activation of the PAF pathway is crucial for PUVA-induced immune suppression (as measured by suppression of delayed type hypersensitivity to Candida albicans) and that it plays a role in skin inflammation and apoptosis. Downstream of PAF, interleukin-10 was involved in PUVA-induced immune suppression but not inflammation. Better understanding of PUVA's mechanisms may offer the opportunity to dissect the therapeutic from the detrimental (ie, carcinogenic) effects and/or to develop new drugs (eg, using the PAF pathway) that act like PUVA but have fewer side effects.

New insight into the inhibition of the inflammatory response to experimental delayed-type hypersensitivity reactions in mice by scropolioside A

Scropolioside A, an iridoid isolated from Scrophularia auriculata ssp. pseudoauriculata, showed anti-inflammatory properties against different experimental models of delayed-type hypersensitivity. This iridoid reduced the oedema induced by oxazolone by 79% (72 h) at 0.5 mg/ear while reducing that induced by sheep red blood cells by 47% (18 h), 45% (24 h) and 36% (48 h) at 10 mg/kg. In vivo it reduced both oedema formation and cell infiltration whereas in vitro it reduced the proliferation of activated T-lymphocytes (IC50 of 67.74 microM). Treatment with scropolioside A (100 microM) 18 and 24 h after phytohemagglutinin stimulation increased the number of cells arrested in the subG(0) phase whereas treatment 3 h after stimulation clearly increased the number of cells that passed to the S phase. Scropolioside A also inhibited the production of prostaglandin E2, leukotriene B4, nitric oxide, interleukin-1beta, interleukin-2, interleukin-4, tumour necrosis factor-alpha and interferon-gamma, but had no effect on the production of interleukin-10. Moreover, it modified the expression of both nitric oxide synthase-2 and cyclooxygenase-2, as well as the activation of nuclear factor-kappaB in RAW 264.7 macrophages.

Cutaneous delayed-type hypersensitivity (DTH) in a multi-formulation comparator trial of the anti-falciparum malaria vaccine candidate RTS,S in rhesus macaques

BACKGROUND

Studies are underway to identify more immunogenic formulations of the existing anti-falciparum malaria vaccine RTS,S/AS02A. To supplement in vitro immunogenicity assays, cutaneous delayed-type hypersensitivity (DTH) may be a useful indicator of functional, cell-mediated immunogenicity.

METHODS

Adult rhesus monkeys were immunized with saline or one of four RTS,S/adjuvant formulations: RTS,S/AS01B, RTS,S/AS02A-standard (current formulation), RTS,S/AS05 or RTS,S/AS06 at 0, 4, and 12 weeks. An additional cohort received RTS,S/AS02A-accelerated, at 0, 1, and 4 weeks. Six months after completing immunizations, five vaccine-relevant antigens (high and low doses) and two controls were administered intradermally. DTH reactivity (induration) was measured at 48 and 72h, and selected sites were biopsied for histological confirmation.

RESULTS

In comparison with RTS,S/AS02A-standard, RTS,S/AS01B and RTS,S/AS05 each had larger mean reactions (induration) at 5 of 10 (p<0.01, at each site) and 1 of 10 (p<0.05, at the single site) vaccine relevant test sites, respectively. Histologically, perivascular mononuclear cell infiltrates, a cardinal feature of DTH, were largest in the RTS,S/AS01B monkeys.

INTERPRETATION

In DTH testing, with histological confirmation, RTS,S/AS01B was immunogenically superior to RTS,S/AS02A-standard and two other novel RTS,S formulations. The DTH outcomes paralleled conventional in vitro cellular immunogenicity assessments in distinguishing among similar RTS,S formulations, even at 6 months after final vaccination.

Semaphorin 7A is a negative regulator of T cell responses

Semaphorins play an essential role in axonal guidance, and emerging evidence points to diverse functions of several Semaphorin family members in the immune system. Semaphorin 7A (Sema7A) promotes axonal growth in the central nervous system. Here, we show that Sema7A also plays a critical role in negative regulation of T cell activation and function. T cells deficient in Sema7A exhibit enhanced homeostatic and antigen-induced proliferative response. Moreover, autoreactive Sema7A-deficient T cells mediate aggressive autoimmune disease. The deficiency in Sema7A leads to defective TCR downmodulation and T cell hyperresponsiveness. These results demonstrate an important role of Sema7A in limiting autoimmune responses and add to growing evidence of shared signaling pathways used by the immune and nervous systems.

Bilateral basal ganglia involvement in a patient with Griscelli syndrome

We report a 6-year-old Iranian boy with silvery-gray hair, eyelashes and the eyebrows who was admitted because of seizures and subsequent stupor. He had previous history of acute hemiparesis at 1 year of age and hepatitis-like syndrome 3 months ago. Microscopic examination of the patient's hair shaft revealed different sized clumps of melanin seen in the center of the shafts. Bone marrow aspiration revealed erythroid hyperplasia and erythrophagocytic cells. Bilateral frontal cortical and subcortical high signal lesions, dirty white matter, high signal areas in the upper pons and in both caudates and lentiform nuclei in T2 WI were the brain MRI findings of the patient. He died in the accelerated phase of Griscelli Syndrome (GS) type 2. To our knowledge we report the first case of GS from Iran.

An orally active reversible inhibitor of cathepsin S inhibits human trans vivo delayed-type hypersensitivity

Cathepsin S is a major histocompatibility complex (MHC) class II associated invariant chain (Ii) degrading enzyme expressed in antigen presenting cells such as B cells and dendritic cells. This enzyme is essential for MHC class II associated antigen processing and presentation to CD4(+) T cells. Compound I, a selective, reversible and orally bioavailable, inhibitor of cathepsin S, with molecular IC(50)=9 nM, has been recently described. We have tested the effects of compound I in a trans vivo model of delayed-type hypersensitivity. Human peripheral blood mononuclear cells (7-10 x 10(6)) from tetanus-sensitized donors were co-injected with tetanus toxoid (0.25 Lf) into C57Bl/6 mouse footpads. At 24 h, significant footpad swelling (+0.024+/-0.001 cm) characterized by an influx of mouse neutrophils and monocytes was observed. Injection of peripheral blood mononuclear cells alone caused negligible swelling (0.002+/-0.0002 cm). Anti-human MHC class II (HLA-DR, DP, DQ) antibody (5 mg/kg, i.p.) inhibited the swelling 91+/-7%, thus demonstrating a role of human antigen presenting cells in this model. Compound I (10, 30, and 100 mg/kg, p.o.) inhibited the response with an ED50 of approximately 18 mg/kg. Compound III, a less active analogue (molecular IC50>20 microM) had no effect. Furthermore, pretreatment of peripheral blood mononuclear cells with 10 nM compound II, an irreversible inhibitor (molecular IC50=11 nM) inhibited swelling 87+/-4%. These findings support the role of cathepsin S in human delayed-type hypersensitivity. Inhibition of cathepsin S with compound I may be useful in the treatment of human autoimmune diseases like rheumatoid arthritis and multiple sclerosis.

Nitric oxide inhibits T cell adhesion and migration by down-regulation of β1-integrin expression in immunologically liver-injured mice

Our previous study has reported that nitric oxide (NO) exerts a protective role in immunologically liver-injured mice induced by delayed-type hypersensitivity to picryl chloride. To explore the mechanism of the protection, we have now examined the effect of NO on T cell adhesion and migration. First, we isolated hepatocytes and nonparenchymal cells from the liver-injured mice and separated the nonparenchymal cells into Kupffer cell-enriched and lymphocyte-enriched populations. When these hepatocytes or the fractions of nonparenchymal cells were co-cultured with spleen T cells of the liver-injured mice in a Transwell system, the adhesive potential of the T cells was significantly inhibited in the presence of hepatocytes or the Kupffer cell-enriched population but not the lymphocyte-enriched population of nonparenchymal cells. This effect was dependent on NO production. The NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA) could reverse this inhibition of cell adhesion and also decrease NO production. To confirm this effect of NO on T cells, we further examined the role of exogenous or endogenous NO on the adhesive activity of the Jurkat T cell line. As a result, the NO donor, S-nitroso-N-acetyl penicillamine (SNAP) caused a dose-dependent inhibition of the adhesion of Jurkat T cells. Furthermore, the binding ability of Jurkat T cells to collagen decreased gradually after co-incubation with macrophages stimulated by LPS+IFN-gamma, an effect which correlated well with the increasing NO level in the medium. Such opposite changes in cell adhesion and in NO production were also markedly reversed by L-NMMA. Moreover, treatment with SNAP reduced adhesion, transmigration, matrix metalloproteinase-9 production and beta1-integrin expression of spleen T cells of the liver-injured mice. Taken together, these findings suggest that NO can function as a down-regulator of T cell mobility, which might be one of the mechanisms by which NO exerts its protective effect in T cell-mediated liver injury.

IL‐18 is redundant in T‐cell responses and in joint inflammation in antigen‐induced arthritis

IL-18 is an important cofactor in Th1 immune responses and it has additional roles in inflammation. Recent reports suggest the contribution of IL-18 to immune responses may vary between mouse strains and immune contexts. We investigated the contribution of IL-18 to T-cell activation and joint inflammation in Ag-induced arthritis (AIA) in C57Bl/6 mice. AIA and cutaneous delayed-type hypersensitivity (DTH) reactions were induced in wild-type (WT) and IL-18-/- C57Bl/6 mice, and Ag-specific T-cell proliferation and IFN-gamma and IL-4 production were measured. The humoral immune response was measured as serum antibody to the disease-initiating Ag, methylated BSA (mBSA). Splenocyte production of IL-6 was measured by ELISA. To confirm the dependence of this model on Th1-cell-mediated immunity, IL-12p40-/- mice were similarly studied. WT mice developed synovitis, joint effusion, cartilage destruction and bone damage associated with induction of DTH, and in vitro Ag-specific T-cell proliferation and IFN-gamma production. Unexpectedly, IL-18-/- mice developed AIA and indices of T-cell activation were similar to those of WT mice. In contrast, IL-12p40-/- mice did not develop AIA, DTH or T-cell activation. WT and IL-18-/- mice, but not IL-12p40-/- mice, developed significantly increased serum antibody to mBSA compared with naive controls. WT and IL-18-/- splenocytes produced high levels of IL-6, whereas IL-12p40-/- cells had significantly lower IL-6 production compared with both. In conclusion, IL-18 is redundant both as a Th1 response cofactor and inflammatory cytokine, whereas IL-12p40-/- is a key cytokine, in AIA in C57Bl/6 mice.

The Human Specific CCR1 Antagonist CP-481,715 Inhibits Cell Infiltration and Inflammatory Responses in Human CCR1 Transgenic Mice

We previously described the in vitro characteristics of the potent and selective CCR1 antagonist, CP-481,715. In addition to being selective for CCR1 vs other chemokine receptors, CP-481,715 is also specific for human CCR1 (hCCR1), preventing its evaluation in classical animal models. To address this, we generated mice whereby murine CCR1 was replaced by hCCR1 (knockin) and used these animals to assess the anti-inflammatory properties of CP-481,715. Cells isolated from hCCR1 knockin mice were shown to express hCCR1 and migrate in response to both murine CCR1 and hCCR1 ligands. Furthermore, this migration is inhibited by CP-481,715 at dose levels comparable to those obtained with human cells. In animal models of cell infiltration, CP-481,715 inhibited CCL3-induced neutrophil infiltration into skin or into an air pouch with an ED50 of 0.2 mg/kg. CP-481,715 did not inhibit cell infiltration in wild-type animals expressing murine CCR1. In a more generalized model of inflammation, delayed-type hypersensitivity, CP-481,715 significantly inhibited footpad swelling and decreased the amount of IFN-gamma and IL-2 produced by isolated spleen cells from sensitized animals. It did not, however, induce tolerance to a subsequent challenge. These studies illustrate the utility of hCCR1 knockin animals to assess the activity of human specific CCR1 antagonists; demonstrate the ability of the CCR1 antagonist CP-481,715 to inhibit cell infiltration, inflammation, and Th1 cytokine responses in these animals; and suggest that CP-481,715 may be useful to modulate inflammatory responses in human disease.

Role of endothelial heparanase in delayed-type hypersensitivity

Heparanase is an endoglycosidase that cleaves heparan sulfate (HS), the main polysaccharide of the basement membrane (BM). HS is responsible for BM integrity and barrier function. Hence, enzymatic degradation of HS in the vascular subendothelial BM is a prerequisite for extravasation of immune cells and plasma components during inflammation. Here, we demonstrate a highly coordinated local heparanase induction upon elicitation of delayed-type hypersensitivity (DTH) reaction in the mouse ear. By monitoring in vivo activation of luciferase gene driven by the heparanase promoter, we demonstrate activation of heparanase transcription at an early stage of DTH. We report that heparanase is produced locally by the endothelium at the site of DTH-associated inflammation. Key DTH mediators, tumor necrosis factor-alpha and interferon-gamma, were found to induce heparanase in cultured endothelial cells. Endothelium emerges as an essential cellular source of heparanase enzymatic activity that, in turn, allows for remodeling of the vascular BM, increased vessel permeability, and extravasation of leukocytes and plasma proteins. In vivo administration of antiheparanase siRNA or an inhibitor of heparanase enzymatic activity effectively halted DTH inflammatory response. Collectively, our results highlight the decisive role of endothelial heparanase in DTH inflammation and its potential as a promising target for anti-inflammatory drug development.

Staphylococcal lipoteichoic acid inhibits delayed-type hypersensitivity reactions via the platelet-activating factor receptor

Staphylococcus aureus infections are known triggers for skin inflammation and can modulate immune responses. The present studies used model systems consisting of platelet-activating factor receptor-positive and -negative (PAF-R-positive and -negative) cells and PAF-R-deficient mice to demonstrate that staphylococcal lipoteichoic acid (LTA), a constituent of Gram-positive bacteria cell walls, acts as a PAF-R agonist. We show that LTA stimulates an immediate intracellular Ca2+ flux only in PAF-R-positive cells. Intradermal injections of LTA and the PAF-R agonist 1-hexadecyl-2-N-methylcarbamoyl glycerophosphocholine (CPAF) induced cutaneous inflammation in wild-type but not PAF-R-deficient mice. Systemic exposure to LTA or CPAF inhibited delayed-type hypersensitivity (DTH) reactions to the chemical dinitrofluorobenzene only in PAF-R-expressing mice. The inhibition of DTH reactions was abrogated by the addition of neutralizing antibodies to IL-10. Finally, we measured levels of LTA that were adequate to stimulate PAF-R in vitro on the skin of subjects with infected atopic dermatitis. Based on these studies, we propose that LTA exerts immunomodulatory effects via the PAF-R through production of the Th2 cytokine IL-10. These findings show a novel mechanism by which staphylococcal infections can inhibit Th1 reactions and thus worsen Th2 skin diseases, such as atopic dermatitis.

Riboflavin in innate and acquired immune responses

OBJECTIVE AND DESIGN

Riboflavin, also known as vitamin B2, is a micronutrient with a key role in maintaining human health. It has also been shown to enhance host resistance to bacterial infections in mice. The aim of this study was to assess the role of vitamin B2 treatment in inflammatory conditions.

SUBJECTS AND METHODS

Three models of inflammatory states were assessed. One of them encompasses neutrophil mediated but T cell/macrophage independent cutaneous inflammation. Another one is delayed type hypersensitivity reaction (DTH), a T cell/macrophage dependent but neutrophil independent inflammatory response. The third one is collagen- induced arthritis, having components from both of the above described reactions. Mice were treated with vitamin B2, administered by peritoneal injections, throughout the course of the experiments.

RESULTS

The granulocyte dependent reaction to olive oil was significantly reduced in vitamin B2 treated mice. In contrast, DTH reactivity and collagen II arthritis were not affected by the treatment.

CONCLUSION

Riboflavin administration affects neutrophil migration but does not alter acquired immune responsiveness.

[Effects of berberine on DNFB-induced delayed type hypersensitivity in mice]

AIM

To investigate the effect of berberine (Ber) on DNFB-induced delayed type hypersensitivity (DTH) and explore the mechanism of the immunosuppression effect of berberine.

METHODS

BALB/c mice were divided into three groups: control group, DTH group, and Ber-treated DTH group. The DTH group was sensitized to DNFB by painting the shaved abdomen with DNFB dissolved in propanone/olive oil. The Ber-treated DTH group was injected (i.p.) with berberine daily for 7 consecutive days, with the total dose of 30 mg/kg. The control group was treated with the solvent without DNFB. All mice were then challenged by painting 10 microL of 2 g/L DNFB on the left ears. The weight of right and left ears was measured at 48 h after challenge. Histological changes of mouse auricles were observed under light microscopy. Violet crystal staining was used to determine the effect of Ber on adhesion of mouse splenic lymphocytes to extracellular matrix (ECM). Annexin-V staining was used to detect the apoptotic rate of the lymphocytes in the lymph nodes.

RESULTS

The results of ear weighting showed that Ber significantly inhibited DTH reaction (P<0.05). Histological observation indicated Ber reduced markedly the infiltration of lymphocytes. The adhesion of T lymphocytes to ECM was also notably decreased by Ber treatment (P<0.05). There was no obvious difference in apoptotic rates of the lymphocytes among Ber-treated DTH group, DTH group and control group (P>0.05).

CONCLUSION

Ber can significantly inhibit the DNFB-induced DTH in mice. The reduced adhesion between mouse T lymphocytes and ECM may be one of the mechanisms of suppression of DTH by Ber.

BAFF augments certain Th1-associated inflammatory responses

B cell-activating factor belonging to the TNF family (BAFF; BLyS) is a critical regulator of B cell maturation and survival, and its overexpression in BAFF transgenic (Tg) mice results in the development of autoimmune disorders. BAFF also affects T cell function through binding to one of the BAFF receptors, BAFF-R. Using BAFF Tg mice, we examined a typical Th1-mediated response, the cutaneous delayed-type hypersensitivity reaction, and found a much greater degree of paw swelling and inflammation than in control mice. Importantly, delayed-type hypersensitivity scores correlated directly with BAFF levels in serum. Conversely, in a Th2-mediated model of allergic airway inflammation, BAFF Tg mice were largely protected and showed markedly reduced Ag-specific T cell proliferation and eosinophil infiltration associated with the airways. Thus, local and/or systemically distributed BAFF affects Th1 and Th2 responses and impacts on the course of some T cell-mediated inflammatory reactions. Our results are consistent with the idea that BAFF augments T cell as well as B cell responses, particularly Th1-type responses. Results in BAFF Tg mice may reflect the situation in certain autoimmune patients or virally infected individuals, because BAFF levels in blood are comparable.

Symptoms and danger signs in acute drug hypersensitivity

Early and rapid recognition of severe adverse drug reactions is essential. Prompt withdrawal of the offending drug is the most important action to minimize morbidity and mortality. Dependent on the type of reaction, e.g. in immediate type reactions instant withdrawal and therapy are mandatory, whereas in delayed reactions diagnosis as early as possible may be life-saving. The skin is an important herald organ and may early signal a severe evolution of a cutaneous reaction or involvement of circulating blood cells or internal organs. A synthesis considering all factors should be made to obtain an early and correct diagnosis.

Exosomes Derived from IL-10-Treated Dendritic Cells Can Suppress Inflammation and Collagen-Induced Arthritis

We have demonstrated previously that local, adenoviral-mediated gene transfer of viral IL-10 to a single joint of rabbits and mice with experimental arthritis can suppress disease in both the treated and untreated contralateral joints. This contralateral effect is mediated in part by APCs able to traffic from the treated joint to lymph nodes as well as to untreated joints. Moreover, injection of dendritic cells (DC) genetically modified to express IL-4 or Fas ligand was able to reverse established murine arthritis. To examine the ability of exosomes derived from immunosuppressive DCs to reduce inflammation and autoimmunity, murine models of delayed-type hypersensitivity and collagen-induced arthritis were used. In this study, we demonstrate that periarticular administration of exosomes purified from either bone marrow-derived DCs transduced ex vivo with an adenovirus expressing viral IL-10 or bone marrow-derived DCs treated with recombinant murine IL-10 were able to suppress delayed-type hypersensitivity responses within injected and untreated contralateral joints. In addition, the systemic injection of IL-10-treated DC-derived exosomes was able suppress the onset of murine collagen-induced arthritis as well as reduce severity of established arthritis. Taken together, these data suggest that immature DCs are able to secrete exosomes that are involved in the suppression of inflammatory and autoimmune responses. Thus DC-derived exosomes may represent a novel, cell-free therapy for the treatment of autoimmune diseases.