Node Proliferation Research Articles

Enhanced formation and survival of CD4+ CD25hi Foxp3+ T-cells in chronic lymphocytic leukemia

Recently, it has been described that patients with chronic lymphocytic leukemia (CLL) have increased numbers of regulatory T (Treg) cells. In the present study, we analysed the mechanism behind Treg cells expansion in CLL. Neither analysis of the T-cell receptor repertoire nor CD45 isoform expression of Treg cells from patients with CLL provided evidence for chronic (tumor) antigenic stimulation as a possible cause for Treg cells expansion in CLL. We found evidence however for increased formation of Treg cells via CD70 costimulation, because we observed that CD40 ligand activated CLL cells (which might be considered a model of lymph node CLL cells) strongly induced CD70-dependent formation of Treg cells. Reverse transcription-multiplex ligation-dependent probe amplification assay expression analysis of 34 apoptosis-regulating genes showed that in comparison with other CD4+ T-cells, Treg cells from both healthy individuals (HD) and patients with CLL had a high expression of pro-apoptotic Noxa and a low expression of anti-apoptotic Bcl-2. Strikingly, Bcl-2 levels of Treg cells in patients with CLL were significantly higher than in HD. Finally, the different apoptotic profile resulted in differences at the functional level, because Treg cells from patients with CLL were more resistant to drug-induced apoptosis than Treg cells from HD. In conclusion, Treg cells in CLL may accumulate both by increased formation, facilitated by CD27-CD70 interaction in the lymph node proliferation centres, and decreased sensitivity to apoptosis because of a shifted Noxa-Bcl-2 balance.

C-Abl kinase inhibitors overcome CD40-mediated drug resistance in CLL: implications for therapeutic targeting of chemoresistant niches

AbstractIn lymph node (LN) proliferation centers in chronic lymphocytic leukemia (CLL), the environment protects from apoptotic and cytotoxic triggers. Here, we aimed to define the molecular basis for the increased drug resistance and searched for novel strategies to circumvent it. The situation in CLL LN could be mimicked by prolonged in vitro CD40 stimulation, which resulted in up-regulation of antiapoptotic Bcl-xL, A1/Bfl-1, and Mcl-1 proteins, and afforded resistance to various classes of drugs (fludarabine, bortezomib, roscovitine). CD40 stimulation also caused ERK-dependent reduction of Bim-EL protein, but ERK inhibition did not prevent drug resistance. Drugs combined with sublethal doses of the BH3-mimetic ABT-737 displayed partial and variable effects per individual CD40-stimulated CLL. The antiapoptotic profile of CD40-triggered CLL resembled BCR-Abl–dependent changes seen in chronic myeloid leukemia (CML), which prompted application of c-Abl inhibitors imatinib or dasatinib. Both compounds, but especially dasatinib, prevented the entire antiapoptotic CD40 program in CLL cells, and restored drug sensitivity. These effects also occurred in CLL samples with dysfunctional p53. Importantly, ex vivo CLL LN samples also displayed strong ERK activation together with high Bcl-xL and Mcl-1 but low Bim levels. These data indicate that CLL cells in chemoresistant niches may be sensitive to therapeutic strategies that include c-Abl inhibitors.

Dichotomy in NF-κb Signaling and Chemoresistance in IgVH Mutated Versus Unmutated CLL Cells Revealed by CD40Ligand/CpG Stimulation

Introduction and aim IgVH mutated (M) and unmutated (UM) Chronic Lymphocytic Leukemia (CLL) cells differ in their response to the TLR-9 ligand CpG. Whereas CpG induces proliferation in UM CLL it induces apoptosis in M CLL cells obtained from peripheral blood (PB). Yet, PB CLL cells are generally not representative of the cycling fraction which resides in lymph node (LN) proliferation centers. In vitro CD40 stimulation of CLL cells enhances NF-κB activity, upregulates anti-apoptotic proteins Bcl-XL and Bfl-1 and results in chemoresistance. These characteristics are highly similar to, and provide a model for, the situation in LN. In the present study we analyzed the effect of CD40 ligation on CpG responses of both IgVH M and UM CLL cells.Methods An in vitro co-culture system of PB CLL cells with 3T3 fibroblasts expressing human CD40L was employed to which soluble CpG was added. Cells, RNA and protein fractions were analyzed with respect to:apoptosis, proliferation and drug sensitivity andNF-κB signaling and downstream targets.Results In both prognostic subgroups 72 hours of CD40 stimulation results in chemoresistance to different classes of drugs (fludarabine, velcade and roscovitine), as we reported before. However, an important difference in chemoresistance was seen when soluble CpG was added to the culture; UM CLL cells remained drug resistant, but M CLL cells now became sensitive. A corresponding dichotomy in NF-κB signaling occurred upon stimulation with CD40L/CpG compared to CD40L alone. M CLL cells showed gradually declining classical and alternative NF-κB activation and the downstream target Bcl-XL, whereas in UM CLL cells NF-κB and Bcl-XL levels remained equal. Interestingly, after treatment with ABT-737, a BH3 mimetic which is very effective against Bcl-XL, also UM CLL cells became sensitive for cytostatic drugs underscoring the importance of anti-apoptotic Bcl-XL. Induction of TNF-α secretion, also a downstream effect of NF-κB activation, took place similarly in both subgroups upon stimulation with CD40L and CpG. We hypothesize that the source of the dichotomy NF-κB activation lays in upstream signaling determinants such as cIAP1/2, NIK and TRAF family members.Conclusions Our data uncover a novel distinction in NF-κB activation and drug susceptibility in mutated versus unmutated CLL cells in a relevant model for LN proliferation centers. Together, they provide a rationale for the development of novel drug regimens targeting the NF-κB pathway to treat UM CLL patients.

Enhanced Formation and Survival of Regulatory T Cells in CLL.

Background. In healthy individuals it has been shown that regulatory T cells (Treg) differentiate from rapidly proliferating memory T cells. Rapid proliferation in combination with high susceptibility to apoptosis, make the Treg population highly dynamic. Tregs are thought to play an important role in immune evasion by malignancies. High Treg numbers in patients with malignancies are often associated with poor prognosis. An important question to be answered is whether tumor cells can promote the expansion and activation of Tregs. Recently it has been described that chronic lymphocytic leukemia (CLL) patients have increased numbers of Treg, with highest Treg frequencies in progressive patients1. The mechanism of this expansion however remains unknown. In the present study, we analysed the mechanism behind Treg expansion in CLL.Results. Neither analysis of the T cell receptor (TCR) repertoire nor CD45 isoform expression of Treg from CLL patients provided evidence for chronic (tumor) antigenic stimulation as a possible cause for Treg expansion in CLL. Furthermore, we found no correlation with CMV serology, which has been demonstrated to influence the CD8+ T cell repertoire in CLL. However, in line with recent studies demonstrating that CD70+ NHL cells are strong inducers of Treg, we found evidence for increased formation of Treg in CLL via CD70 costimulation. We observed that CD40 ligand activated CLL cells (which might be considered a model for lymph node CLL cells2) strongly induced CD70-dependent formation of Treg. RT-MLPA expression analysis of 34 apoptosis-regulating genes showed that in comparison to other CD4+ T cells, Treg of both healthy individuals and CLL patients had a high expression of pro-apoptotic Noxa and a low expression of anti-apoptotic Bcl-2. Strikingly, Bcl-2 levels of Treg in CLL patients were significantly higher than in healthy individuals. Finally, the different apoptotic profile resulted in differences at the functional level, since Treg from CLL patients were more resistant to drug-induced apoptosis than Treg from healthy individuals.Conclusion. Treg in CLL may accumulate both by increased formation, facilitated by CD27-CD70 interaction in the lymph node proliferation centres, and decreased sensitivity to apoptosis due to a shifted Noxa-Bcl-2 balance. Since high Treg numbers might negatively affect the course of disease, targeting these mechanisms may provide additional therapeutic approaches in CLL.

L‐Selectin‐deficient SJL and C57BL/6 mice are not resistant to experimental autoimmune encephalomyelitis

L-selectin has been suggested to play a role in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. Here we demonstrate that L-selectin(-/-) SJL mice are susceptible to proteolipid protein (PLP)-induced EAE because the compromised antigen-specific T cell proliferation in peripheral lymph nodes is fully compensated by the T cell response raised in their spleen. Transfer of PLP-specific T cells into syngeneic recipients induced EAE independent of the presence or absence of L-selectin on PLP-specific T cells or in the recipient. Leukocyte infiltration into the central nervous system parenchyma was detectable independent of the mode of disease induction and the presence or absence of L-selectin. In addition, we found L-selectin(-/-) C57BL/6 mice to be susceptible to myelin oligodendrocyte glycoprotein-induced EAE. Taken together, we demonstrate that in SJL and C57BL/6 mice L-selectin is not required for EAE pathogenesis. The apparent discrepancy of our present observation to previous findings, demonstrating a role of L-selectin in EAE pathogenesis in C57BL/6 mice or myelin-basic protein (MBP)-specific TCR-transgenic B10.PL mice, may be attributed to background genes rather than L-selectin and to a unique role of L-selectin in EAE pathogenesis in MBP-TCR-transgenic mice.

Early Divergence in Lymphoid Tissue Apoptosis between Pathogenic and Nonpathogenic Simian Immunodeficiency Virus Infections of Nonhuman Primates

The events that contribute to the progression to AIDS during the acute phase of a primate lentiviral infection are still poorly understood. In this study, we used pathogenic and nonpathogenic simian models of simian immunodeficiency virus (SIV) infection of rhesus macaques (RMs) and African green monkeys (AGMs), respectively, to investigate the relationship between apoptosis in lymph nodes and the extent of viral replication, immune activation, and disease outcome. Here, we show that, in SIVmac251-infected RMs, a marked increased in lymphocyte apoptosis is evident during primary infection at the level of lymph nodes. Interestingly, the levels of apoptosis correlated with the extent of viral replication and the rate of disease progression to AIDS, with higher apoptosis in RMs of Indian genetic background than in those of Chinese origin. In stark contrast, no changes in the levels of lymphocyte apoptosis were observed during primary infection in the nonpathogenic model of SIVagm-sab infection of AGMs, despite similarly high rates of viral replication. A further and early divergence between SIV-infected RMs and AGMs was observed in terms of the dynamics of T- and B-cell proliferation in lymph nodes, with RMs showing significantly higher levels of cycling cells (Ki67(+)) in the T-cell zones in association with relatively low levels of Ki67(+) in the B-cell zones, whereas AGMs displayed a low frequency of Ki67(+) in the T-cell area but a high proportion of Ki67(+) cells in the B-cell area. As such, this study suggests that species-specific host factors determine an early immune response to SIV that predominantly involves either cellular or humoral immunity in RMs and AGMs, respectively. Taken together, these data are consistent with the hypotheses that (i) high levels of T-cell activation and lymphocyte apoptosis are key pathogenic factors during pathogenic SIV infection of RMs and (ii) low T-cell activation and apoptosis are determinants of the AIDS resistance of SIVagm-infected AGMs, despite high levels of SIVagm replication.

Host Indoleamine 2,3-Dioxygenase Is a Critical Regulator of Acute GVHD Lethality.

Graft versus host disease (GVHD), the major cause of morbidity and mortality after bone marrow transplant (BMT), is initiated following activation of donor T cells by host antigen presenting cells (APCs). The immunosuppressive enzyme indoleamine 2,3-dioxygenase (IDO) is expressed by APCs and parenchymal cells and is further inducible by inflammation. We investigated whether lethal conditioning and GVHD induce IDO and if IDO prevents tissue injury by suppressing immune responses at the induction site. Using a fully MHC-mismatched murine GVHD model, we determined that IDO is a critical regulator of GVHD, most strikingly in the colon, where epithelial cells dramatically upregulated IDO expression during GVHD. No IDO upregulation was detected in mice that received irradiation only or irradiation and T cell-depleted BM without added alloreactive T cells. When mice with a genetic ablation of the IDO gene (IDO−/−) were used as recipients of BM and T cells, they suffered accelerated GVHD lethality compared to wild-type recipients, displaying increased colonic inflammation and T cell infiltration. This was true using grafts of either CD4+ T cells or combined CD4+ and CD8+ T cells. In addition, the IDO inhibitor 1-methyltryptophan caused accelerated GVHD in wild-type recipients. Lethality was not due to increased radiation sensitivity, as sublethally irradiated IDO−/− recipients showed no morbidity, and syngeneic BM was capable of rescuing lethally irradiated IDO−/− recipients. GVHD protection was not mediated by early control of T cell proliferation or apoptosis in lymph nodes or spleen. Furthermore, IDO did not affect expression of T cell effector molecules in lymphoid organs. Though studies have suggested a link between IDO and T regulatory cell (Treg) function, Treg depletion of donor grafts did not abrogate the IDO effect, indicating donor Tregs are not required for the suppressive function of IDO. Conversely, cultured Tregs added to the graft delayed GVHD in IDO−/− recipients, proving Tregs do not require host IDO for their function in this model. Instead, colons from IDO−/− hosts contained more proliferating CD4+ cells than wild-type colons after transplant. Together, this evidence suggests that in GVHD IDO acts primarily at the site of its expression to decrease effector T cell proliferation, diminish colonic inflammation, and reduce disease severity. These studies are the first to identify a function for IDO in GVHD lethality and suggest that modulation of the IDO pathway may be an effective strategy for treatment of this disease.

Bcl-xS Is an Important Pro-Apoptotic Bcl-2 Family Member in Chronic Lymphocytic Leukaemia and Its Expression Is Regulated by SAM68, hnRNP-F and hnRNP-H.

We have previously shown that the pro-apoptotic Bcl-x isoform Bcl-xS is induced in chronic lymphocytic leukaemia cells during spontaneous and drug induced apoptosis to a greater extent than other pro-apoptotic Bcl-2 family members including Bim, Puma and Noxa. Puma, Noxa and also Bid were induced strongly by stimulation with CD40 ligand, in culture conditions causing CLL cell proliferation and survival, and associated with strong induction of the pro-survival Bcl-x isoform, Bcl-xL. Immunohistochemistry demonstrates Bcl-xL expression in lymph node proliferation centres. We, therefore, conclude that splicing of Bcl-x mRNA is important for regulation of CLL survival such that Bcl-xL is required during proliferation in the lymph node or bone marrow microenvironment, but Bcl-xS is induced during apoptosis. Splicing of Bcl-x mRNA in HeLa cells is known to be controlled by RNA binding proteins including SAM68, heterogeneous ribonucleoprotein-F (hnRNP-F) and hnRNP-H, but expression and regulation of these molecules has not been investigated in CLL. We have demonstrated that expression of hnRNP-F and hnRNP-H decline in association with an increase in Bcl-xS expression. Conversely expression of the ribonucleoproteins is maintained (relative to expression in freshly isolated peripheral blood CLL cells) or increases on CD40 stimulation. SAM68 showed a similar pattern of expression with increased expression on CD40 stimulation and decreased under conditions of apoptosis. Phosphorylation of SAM68 can control the RNA binding activity of this molecule. We immunoprecipitated SAM68 from freshly isolated CLL cells and cells that had been cultured with CD40 ligand (to promote proliferation) or on tissue culture plastic (to promote apoptosis) for 2 days. Westerns of the immunoprecipitated protein were probed with an anti-phosphotyrosine antibody. We found variable patterns: phosphorylation was uniformly present in cells cultured on plastic (4/4 cases) but was only detectable in freshly isolated cells in 1 case and on CD40 stimulation in 2 cases. We conclude that the RNA binding proteins hnRNP-F, hnRNP-H and SAM68 have important roles in controlling Bcl-x splicing in CLL cells, and that their effects are largely due to variation in expression level rather than phosphorylation. Strategies to bias production of pro-apoptotic Bcl-xS using siRNA either directed against Bcl-xL mRNA or against RNA binding proteins may be therapeutically useful.

The role of CD8+CD28 regulatory cells in suppressing myasthenia gravis-associated responses by a dual altered peptide ligand.

Myasthenia gravis (MG) and experimental autoimmune MG are T cell-dependent antibody-mediated autoimmune diseases. A dual altered peptide ligand (APL), composed of the tandemly arranged two single amino acid analogs of two myasthenogenic peptides, p195-212 and p259-271, down-regulated in vitro and in vivo MG-associated T cell responses. In the present study, we investigated the role of CD8(+)CD28(-) regulatory cells in the mechanism of action of the dual APL. We demonstrated that treatment of mice with the dual APL concomitant with immunization with a myasthenogenic peptide resulted in an increased population of CD8(+)CD28(-) cells that express forkhead box P3 (Foxp3). The dual APL inhibited the proliferation of lymph node (LN) cells of the Torpedo acetylcholine receptor-immunized WT C57BL/6 mice, whereas the inhibition was abrogated in CD8(-/-) knockout mice. Moreover, the dual APL did not inhibit the secretion of IFN-gamma by LN cells from CD8(-/-) mice immunized with Torpedo acetylcholine receptor. However, the mRNA expression of IL-10 and TGF-beta by LN cells from CD8(-/-) mice was up-regulated similarly to that of the WT mice. Furthermore, the dual APL elevated the proapoptotic markers caspases 3 and caspase 8, whereas it down-regulated the antiapoptotic marker Bcl-xL in both CD8(-/-) and WT mice. Finally, the dual APL-induced CD4(+)CD25(+)Foxp3(+) cells were up-regulated in CD8(-/-) mice to a similar extent to that observed in the WT mice. Thus, we suggest that CD8(+)CD28(-) regulatory cells play a partial role in the mechanism of action by which the dual APL suppresses experimental autoimmune MG-associated T cell responses.

IL-10-Inducing Adjuvants Enhance Sublingual Immunotherapy Efficacy in a Murine Asthma Model

Background: IL-10-inducing adjuvants could enhance the efficacy of allergy vaccines in establishing allergen-specific tolerance.The aim of this study wasto identify such adjuvants using in vitro cultures of human and murine cells and to evaluate them in a therapeutic murine model of sublingual immunotherapy (SLIT). Methods: Adjuvants stimulating IL-10 gene expression by human or murine immune cells were tested sublingually in BALB/c mice sensitized to ovalbumin (OVA), assessing the reduction in airway hyperresponsiveness (AHR) by whole-body plethysmography. The induction of regulatory T cells (T_reg) was evaluated using phenotypic and functional assays. T-cell proliferation in cervical lymph nodes (LNs) was assessed following intravenous transfer of CFSE-labelled OVA-specific T cells and FACS analysis. Results: A combination of 1,25-dihydroxyvitamin D3 plus dexamethasone (VitD3/Dex) as well as Lactobacillus plantarum were found to induce IL-10 production by human and murine dendritic cells (DCs). The former inhibits LPS-induced DC maturation, whereas L. plantarum induces DC maturation. Following stimulation with VitD3/Dex-pretreated DCs, CD4+ naïve T cells exhibit a T_reg profile.In contrast, a Th1/T_reg pattern of differentiation is observed in the presence of DCs treated with L. plantarum. Both adjuvants significantly enhance SLIT efficacy in mice, in association with either induction of Foxp3+ T_reg cells (for VitD3/Dex) or proliferation of OVA-specific T cells in cervical LNs (for L. plantarum). Conclusions: Both VitD3/Dex and L. plantarum polarize naïve T cells towards IL-10-expressing T cells, through distinct mechanisms. As adjuvants, they both enhance SLIT efficacy in a murine asthma model.

Attenuation of Experimental Autoimmune Myositis by Blocking ICOS-ICOS Ligand Interaction

Polymyositis (PM) is an acquired, systemic, connective tissue disease characterized by the proximal muscle weakness and infiltration of mononuclear cells into the affected muscles. To understand its etiology and immunopathogenesis, appropriate animal model is required. It has been demonstrated that immunization with native human skeletal C protein induces severe and reproducible experimental autoimmune myositis (EAM) in Lewis rats, and that the muscle inflammatory lesions in the EAM mimic those of human PM. In the present study, we prepared recombinant skeletal C protein fragment and succeeded in inducing as severe EAM as that by native C protein. We found ICOS expression on muscle fiber-infiltrating T cells in the EAM rats, but not in normal rats. Treatment with anti-ICOS mAb reduced incidence and severity of myositis; decreased the number of muscle-infiltrating CD11b/c+, TCR+, and CD8a+ cells; and inhibited the expression of IL-1alpha and CCL2 in the hamstring muscles of the EAM rats. However, the treatment neither inhibited serum anti-C protein IgG level, C protein-induced proliferation of lymph node (LN) cells, or LN T cells, nor production of IFN-gamma by C protein-stimulated LN cells in EAM rats. These data indicate that analysis of C protein-induced EAM provides not only insights into pathogenesis of PM, but also useful information regarding development of effective immunotherapy against the disease. ICOS-ICOS ligand interaction would be a novel therapeutic target for PM.

Argyrophilic Nucleolar Organizing Regions and Ki67 Equally Reflect Proliferation in Fine Needle Aspirates of Normal, Hyperplastic, Inflamed, and Neoplastic Canine Lymph Nodes (n = 101)

Background: The count of argyrophilic nucleolar organizing regions (AgNOR) has been considered a useful variable that reflects cellular proliferation in canine lymph nodes, but it has not been compared with other markers of proliferation. Hypothesis: Ki67 and AgNORs are equally useful as markers of tissue proliferation in fine needle aspirates of canine lymph nodes. Animals: A total of 101 dogs.Material and Methods: Prospective, observational study of a convenience sample of dogs. Two smears were prepared for a May‐Gruenwald‐Giemsa stain and a Ki67/AgNOR double stain. In addition, CD3/CD79a immunostaining was performed when cytologic examination revealed a lymphoma. The dogs were grouped as normal (n = 26), reactive hyperplasia (n = 25), lymphadenitis (n = 31), and lymphoma (n = 19), based on the physical examination and the cytologic findings. The AgNOR count/cell, AgNOR area/cell and the percentage of cells staining positive for Ki67 were evaluated in 100–167 cells (median, 113 cells) by using automatic image analysis. Results: Mean (SD) AgNOR counts/cell were 1.36 6 0.19 in normal dogs, 1.55 ± 0.26 in lymphadenitis, 1.65 ± 0.32 in reactive hyperplasia, and 3.67 ± 1.08 in lymphoma. The percentage of Ki67 positive cells was 2.67 ± 0.99% in normal lymph nodes, 5.04 ± 3.34% in lymphadenitis, 5.36 ± 2.14% in reactive hyperplasia, and 30.2 ± 10.8% in lymphoma. All variables were significantly higher in dogs with lymphoma compared with the other groups (P < .0001). The sensitivity and the specificity of the AgNOR count for diagnosing lymphoma were 95 and 96% at a cutoff value of .2.04 AgNORs/cell. The cutoff value for the Ki67 positive cells was .10.40% (sensitivity, 95%; specificity, 98%).Conclusion and Clinical Importance: The results indicated that both AgNOR and Ki67 counts were good diagnostic tools for assessment of proliferation in aspirates of canine lymph nodes.

Immunomodulation by neural stem cells

Neural (stem) cell transplantation has been proposed as a means of cell replacement therapy. Multipotential neural precursor cells (NPCs) that expand in floating spheres, and are (partially) committed to a glial fate, showed excellent remyelinating properties in a focal, chemically induced demyelinated lesion in the rat spinal cord. When transplanted into the CNS of rodents with acute and chronic EAE the NPCs were attracted by the inflammatory process to migrate exclusively into inflamed white matter but not into adjacent gray matter. Following magnetic labeling, mouse NPCs and human ESC-derived neural precursors' migration was detected by high-resolution magnetic resonance images. Intraventricular transplantation of neural spheres attenuated brain inflammation in acute and chronic EAE, reduced the clinical severity of disease, and reduced demyelination and axonal pathology. Intravenous (IV) NPC injection also inhibited EAE and reduced CNS inflammation and tissue injury. However, NPCs did not enter the CNS but were transiently found in lymph nodes and spleen, where they inhibited the activation and proliferation of T cells and markedly reduced their encephalitogenicity. Thus, IV administration of neural precursors inhibits EAE by a peripheral immunosuppression, involving a profound bystander inhibitory effect of NPCs on T cell activation and proliferation in lymph nodes. In conclusion, neural precursor cells exert an immunomodulatory effect that inhibits CNS inflammation. Cell therapy in MS should be optimized to utilize both regenerative and immunologic properties of the cells.

Scavenger Receptors SR-AI/II and MARCO Limit Pulmonary Dendritic Cell Migration and Allergic Airway Inflammation

The class A scavenger receptors (SR-A) MARCO and SR-AI/II are expressed on lung macrophages (MPhis) and dendritic cells (DCs) and function in innate defenses against inhaled pathogens and particles. Increased expression of SR-As in the lungs of mice in an OVA-asthma model suggested an additional role in modulating responses to an inhaled allergen. After OVA sensitization and aerosol challenge, SR-AI/II and MARCO-deficient mice exhibited greater eosinophilic airway inflammation and airway hyperresponsiveness compared with wild-type mice. A role for simple SR-A-mediated Ag clearance ("scavenging") by lung MPhis was excluded by the observation of a comparable uptake of fluorescent OVA by wild-type and SR-A-deficient lung MPhis and DCs. In contrast, airway instillation of fluorescent Ag revealed a significantly higher traffic of labeled DCs to thoracic lymph nodes in SR-A-deficient mice than in controls. The increased migration of SR-A-deficient DCs was accompanied by the enhanced proliferation in thoracic lymph nodes of adoptively transferred OVA-specific T cells after airway OVA challenge. The data identify a novel role for SR-As expressed on lung DCs in the down-regulation of specific immune responses to aeroallergens by the reduction of DC migration from the site of Ag uptake to the draining lymph nodes.

Heligmosomoides polygyrus: Decreased apoptosis in fast responder FVB mice during infection

Primary infection with Heligmosomoides polygyrus in some strains of mice is chronic although fast responder mouse strains eliminate the parasite in a short period of time. The reason for the differences is unknown. In this study apoptosis, proliferation, IL-2 and IL-6 production of mesenteric lymph node (MLN) and spleen cells in vitro from fast (FVB) and slow (C57Bl/6) responder mice were compared during H. polygyrus infection. FVB cells showed decreased apoptosis, more proliferation and more cytokine production than cells from C57Bl/6 mice during infection. At the beginning of infection in C57Bl/6 mice the apoptosis of CD4 + but not CD8 + cells significantly increased in MLN and spleen cell cultures. Apoptosis, when the first immune signal is given by infective larvae, might play an important role in the modulation of the response in slow responder mice.

Inhalation of glutamic acid decarboxylase 65-derived peptides can protect against recurrent autoimmune but not alloimmune responses in the non-obese diabetic mouse

Systemic administration of islet-derived antigens has been shown to protect against diabetes in the non-obese diabetic (NOD) mouse by the induction of antigen-specific regulatory T cells. Bystander regulation to related and unrelated islet-derived antigens (intramolecular and intermolecular recognition) in this context is recognized. We tested if intranasal administration of glutamic acid decarboxylase 65 (GAD 65)-derived peptides could protect against both autoimmune and, through bystander regulation, alloimmune responses in a NOD mouse model. Spontaneously diabetic female NOD mice underwent islet transplantation from either C57Bl/6 or NOD islet donors. Islet recipients were treated with intranasal GAD 65-derived peptides or control (ovalbumin) peptide pre- and post-transplantation. In-vitro analysis of the effect of inhalation was defined using lymph node proliferation assays and supernatant analysis for cytokines. GAD 65-derived peptide inhalation resulted in significant protection against recurrent autoimmune disease, with the generation of an interleukin (IL)-10-producing immune phenotype in a syngeneic islet transplant model. This phenotype, however, was not robust enough to protect against alloimmune responses. Inhalation of GAD-derived peptides induces an immunoregulatory response that protects against recurrent autoimmune, but not alloimmune responses in the NOD mouse.

Argyrophilic Nucleolar Organizing Regions and Ki67 Equally Reflect Proliferation in Fine Needle Aspirates of Normal, Hyperplastic, Inflamed, and Neoplastic Canine Lymph Nodes (n  =  101)

The count of argyrophilic nucleolar organizing regions (AgNOR) has been considered a useful variable that reflects cellular proliferation in canine lymph nodes, but it has not been compared with other markers of proliferation. Ki67 and AgNORs are equally useful as markers of tissue proliferation in fine needle aspirates of canine lymph nodes. A total of 101 dogs. Prospective, observational study of a convenience sample of dogs. Two smears were prepared for a May-Gruenwald-Giemsa stain and a Ki67/AgNOR double stain. In addition, CD3/CD79a immunostaining was performed when cytologic examination revealed a lymphoma. The dogs were grouped as normal (n = 26), reactive hyperplasia (n = 25), lymphadenitis (n = 31), and lymphoma (n = 19), based on the physical examination and the cytologic findings. The AgNOR count/cell, AgNOR area/cell and the percentage of cells staining positive for Ki67 were evaluated in 100-167 cells (median, 113 cells) by using automatic image analysis. Mean (SD) AgNOR counts/cell were 1.36 +/- 0.19 in normal dogs, 1.55 +/- 0.26 in lymphadenitis, 1.65 +/- 0.32 in reactive hyperplasia, and 3.67 +/- 1.08 in lymphoma. The percentage of Ki67 positive cells was 2.67 +/- 0.99% in normal lymph nodes, 5.04 +/- 3.34% in lymphadenitis, 5.36 +/- 2.14% in reactive hyperplasia, and 30.2 +/- 10.8% in lymphoma. All variables were significantly higher in dogs with lymphoma compared with the other groups (P < .0001). The sensitivity and the specificity of the AgNOR count for diagnosing lymphoma were 95 and 96% at a cutoff value of >2.04 AgNORs/cell. The cutoff value for the Ki67 positive cells was >10.40% (sensitivity, 95%; specificity, 98%). The results indicated that both AgNOR and Ki67 counts were good diagnostic tools for assessment of proliferation in aspirates of canine lymph nodes.

Effect of Rebamipide on the Colonic Barrier in Interleukin-10-Deficient Mice

Our aim was to study the effect of a mucosal protective agent, rebamipide, on the colonic barrier and the immune response in colitis-prone interleukin-10-deficient (IL-10-/-) C57BL/6 mice infected with Helicobacter hepaticus. After sacrifice, in all mice, control, or previously infected with H. hepaticus, or previously infected and treated with rebamipide enema, a histological examination of colonic samples was performed, intestinal permeability was studied in Ussing chamber, and mesenteric lymph node proliferation and cytokine secretion were measured. Mice treated with rebamipide presented a reinforcement of the distal colonic epithelial barrier, an increase of mesenteric lymph node cells proliferation, and of IFNgamma and IL-12 secretion. These results indicate that in IL-10-/- mice with mild colitis, rectally administered rebamipide reinforces the distal colonic barrier and has a slight Th1 immuno-stimulatory effect on mesenteric lymph node cells. These properties could be helpful in the management of some inflammatory bowel diseases.

Treatment with total alkaloids from Radix Linderae reduces inflammation and joint destruction in type II collagen-induced model for rheumatoid arthritis

Radix Linderae, the dry roots of Lindera aggregata (Sims) Kosterm., is frequently used in traditional Chinese medicine. It contains alkaloids, volatile oils and sesquiterpene esters. In the present study, we investigated the therapeutic potential and underlying mechanisms of the total alkaloids from Radix Linderae (TARL) on collagen II (CII)-induced arthritis (CIA) in mice. TARL (50, 100 and 200 mg/kg), orally administered on the same day of an antigen challenge for 20 consecutive days, alleviated disease severity in a dose-dependent manner but did not significantly affect body weights. The TARL treatment reduced the serum level of anti-CII IgG and suppressed the delayed type hypersensitivity evaluated by its effect against CII-induced ear swelling. TARL also protected joint destruction based on the evidence of reducing the histopathological scores. Furthermore, TARL suppressed CII- and concanavalin A-stimulated lymphocyte proliferation in popliteal lymph nodes, where are close to the affected joints in CIA. These data suggest that TARL is a potential therapeutic agent for rheumatoid arthritis that suppresses inflammation and protects joints from destruction.

Contribution of toxins to the pathogenesis of inhalational anthrax

Inhalational anthrax is a life-threatening infectious disease of considerable concern, especially as a potential bioterrorism agent. Progress is gradually being made towards understanding the mechanisms used by Bacillus anthracis to escape the immune system and to induce severe septicaemia associated with toxaemia and leading to death. Recent advances in fundamental research have revealed previously unsuspected roles for toxins in various cell types. We summarize here pathological data for animal models and macroscopic histological examination data from recent clinical records, which we link to the effects of toxins. We describe three major steps in infection: (i) an invasion phase in the lung, during which toxins have short-distance effects on lung phagocytes; (ii) a phase of bacillus proliferation in the mediastinal lymph nodes, with local effects of toxins; and (iii) a terminal, diffusion phase, characterized by a high blood bacterial load and by long-distance effects of toxins, leading to host death. The pathophysiology of inhalational anthrax thus involves interactions between toxins and various cell partners, throughout the course of infection.