Ascophyllan purified from Ascophyllum nodosum induces Th1 and Tc1 immune responses by promoting dendritic cell maturation

Marine-derived sulfated polysaccharides have been shown to possess certain anti-virus, anti-tumor, anti-inflammatory and anti-coagulant activities. However, the in vivo immunomodulatory effects of marine-derived pure compounds have been less well characterized. In this study, we investigated the effect of ascophyllan, a sulfated polysaccharide purified from Ascophyllum nodosum, on the maturation of mouse dendritic cells (DCs) in vitro and in vivo. Ascophyllan induced up-regulation of co-stimulatory molecules and production of pro-inflammatory cytokines in bone marrow-derived DCs (BMDCs). Moreover, in vivo administration of ascophyllan promotes up-regulation of CD40, CD80, CD86, MHC class I and MHC class II and production of IL-6, IL-12 and TNF-α in spleen cDCs. Interestingly, ascophyllan induced a higher degree of co-stimulatory molecule up-regulation and pro-inflammatory cytokine production than fucoidan, a marine-derived polysaccharide with well-defined effect for promoting DC maturation. Ascophyllan also promoted the generation of IFN-γ-producing Th1 and Tc1 cells in the presence of DCs in an IL-12-dependent manner. Finally, myeloid differentiation primary response 88 (MyD88) signaling pathway was essential for DC maturation induced by ascophyllan. Taken together, these results demonstrate that ascophyllan induces DC maturation, and consequently enhances Th1 and Tc1 responses in vivo. This knowledge could facilitate the development of novel therapeutic strategies to combat infectious diseases and cancer.

Lactoferrin and necrotizing enterocolitis

Lactoferrin (LF) is a multifunctional protein and a member of the transferrin family. LF and lysozyme in breast milk kill bacteria. In the stomach, pepsin digests and releases a potent peptide antibiotic called lactoferricin from native LF. The antimicrobial characteristics of LF may facilitate a healthy intestinal microbiome. LF is the major whey in human milk; its highest concentration is in colostrum. This fact highlights early feeding of colostrum and also fresh mature milk as a way to prevent necrotizing enterocolitis.

Current views on the roles of Th1 and Th17 cells in experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are autoimmune demyelinating diseases of the central nervous system (CNS). Interferon-gamma-producing Th1 and interleukin-17-producing Th17 CD4(+) T helper (Th) cells mediate disease pathogenesis in EAE and likely in MS as well. However, the relative contribution of each Th subset to autoimmune processes in the CNS remains unclear. Emerging data suggest that both Th1 and Th17 cells contribute to CNS autoimmunity, albeit through different mechanisms. A better understanding of the roles that Th1 and Th17 cells play in autoimmune inflammation will be helpful in developing new therapeutic approaches. In this review, we discuss recent findings on the roles of Th1 and Th17 cells in the pathogenesis of EAE.

Polarization of protective immunity induced by replication-incompetent adenovirus expressing glycoproteins of pseudorabies virus

Replication-incompetent adenoviruses expressing three major glycoproteins (gB, gC, and gD) of pseudorabies virus (PrV) were constructed and used to examine the ability of these glycoproteins to induce protective immunity against a lethal challenge. Among three constructs, recombinant adenovirus expressing gB (rAd-gB) was found to induce the most potent immunity biased to Th1-type, as determined by the IgG isotype ratio and the profile of the Th1/Th2 cytokine production. Conversely, the gC-expressing adenovirus (rAd-gC) revealed Th2-type immunity and the gD-expressing adenovirus (rAd-gD) induced lower levels of IFN-? and IL-4 production than other constructs, except IL-2 production. Mucosal delivery of rAd-gB induced mucosal IgA and serum IgG responses and biased toward Th2-type immune responses. However, these effects were not observed in response to systemic delivery of rAd-gB. In addition, rAd-gB appeared to induce effective protective immunity against a virulent viral infection, regardless of whether it was administered via the muscular or systemic route. These results suggest that administration of replication-incompetent adenoviruses can induce different types of immunity depending on the expressed antigen and that recombinant adenoviruses expressing gB induced the most potent Th1-biased humoral and cellular immunity and provided effective protection against PrV infection.

Lipid peroxidation-derived aldehyde-protein adducts contribute to trichloroethene-mediated autoimmunity via activation of CD4+ T cells

Lipid peroxidation is implicated in the pathogenesis of various autoimmune diseases. Lipid peroxidation-derived aldehydes such as malondialdehyde (MDA) and 4-hydroxynonenal (HNE) are highly reactive and bind to proteins, but their role in eliciting an autoimmune response and their contribution to disease pathogenesis remain unclear. To investigate the role of lipid peroxidation in the induction and/or exacerbation of autoimmune response, 6-week-old autoimmune-prone female MRL+/+ mice were treated for 4 weeks with trichloroethene (TCE; 10 mmol/kg, ip, once a week), an environmental contaminant known to induce lipid peroxidation. Sera from TCE-treated mice showed significant levels of antibodies against MDA-and HNE-adducted proteins along with antinuclear antibodies. This suggested that TCE exposure not only caused increased lipid peroxidation, but also accelerated autoimmune responses. Furthermore, stimulation of cultured splenic lymphocytes from both control and TCE-treated mice with MDA-adducted mouse serum albumin (MDA-MSA) or HNE-MSA for 72 h showed significant proliferation of CD4+ T cells in TCE-treated mice as analyzed by flow cytometry. Also, splenic lymphocytes from TCE-treated mice released more IL-2 and IFN-gamma into cultures when stimulated with MDA-MSA or HNE-MSA, suggesting a Th1 cell activation. Thus, our data suggest a role for lipid peroxidation-derived aldehydes in TCE-mediated autoimmune responses and involvement of Th1 cell activation.

Delivery of antigen in allogeneic cells preferentially generates CD(4+) Th1 cells

We have examined the possibility of evoking antigen-specific T cell immune response by using allogeneic cells as a source of adjuvant and also as a vehicle to deliver antigen. The mice were immunized with different preparations of antigen-pulsed allogeneic and syngeneic splenocytes. It was observed during the study that the animals immunized with antigen-pulsed mitomycin C treated allogeneic cells elicited antigen specific CD(4+) Th1 cell response. Predominant release of IL-2, interferon (IFN)-gamma and IgG2a-isotype also occurred. In contrast, mice immunized with antigen-pulsed syngeneic cells chiefly enhanced the production of interleukin (IL)-4 and IgG1-isotype. Further, allogeneic macrophages induced better T cell response than B cells or splenocytes and prominently induced the expression of B7-1 and B7-2. Immunization with antigen-pulsed macrophages provided better recall responses compared to B cells. This was manifested by the high LFA-1alpha and low CD45RB expression on T cells. Because it is already known that mitomycin C-treated cells undergo apoptosis and dendritic cells engulf apoptotic cells, we therefore propose that generation of T cell response using antigen-pulsed allogeneic cells may be due to the engulfment of these cells by dendritic cells, which may then process and present antigen entrapped in allogeneic cells to activate naive CD(4+) T cells and differentiate them to Th1 cells. This study therefore provides a rational basis for manipulating antigen-specific responses by immunizing with antigen-pulsed allogeneic cells.

Increased serum levels of interferon-gamma-inducible protein 10 and monokine induced by gamma interferon in patients with haemophagocytic lymphohistiocytosis

We measured serum interferon-gamma-inducible protein 10 (IP-10) and monokine induced by gamma interferon (MIG) levels to investigate the role of these molecules in the pathophysiology of haemophagocytic lymphohistiocytosis (HLH). Serum IP-10 and MIG levels were significantly increased in patients with active HLH compared with those of healthy controls. Serum MIG levels decreased gradually during the course of disease in a patient who recovered without therapy. On the other hand, rapid reduction of MIG and IP-10 levels was observed after chemotherapy in a patient with severe HLH. IP-10 and MIG mRNA expression was enhanced in liver and spleen, and IP-10 mRNA expression was enhanced in bone marrow in the patients, suggesting activated macrophages that infiltrated in these organs as one of the main producers of these cytokines. Serum IP-10 and MIG levels showed a significant correlation with serum IFN-gamma levels. In addition, these chemokines had a significant correlation with fever and serum LDH levels, which are clinical indicators of disease activity of HLH. These results suggest that IP-10 and MIG which are produced by activated macrophages by the stimulation of IFN-gamma, play an important role in the pathophysiology of HLH, by recruitment of activated Th1 cells into the tissues or organs.

Characterization of bronchoalveolar lavage T cell subsets in sarcoidosis on the basis of CD57, CD4 and CD8

T cells expressing CD57 (a natural killer cell marker) with interferon-gamma (IFN-gamma) producing capacity increase under various conditions. CD57+ T cells are also present in the bronchoalveolar lavage fluid (BALF) of sarcoidosis, and several phenotypical and functional analyses of these cells have been reported. In the present study, BALF T cells obtained from 52 patients with sarcoidosis were classified further into CD4+CD57+ T cells, CD4+CD57- T cells, CD8+CD57+ T cells and CD8+CD57- T cells and their phenotypes and functional characteristics were assessed. Substantial proportions of these T cell subsets expressed natural killer cell markers CD161 and CD122. The biased expansion of Vbeta2 T cells was observed in both CD4+CD57+ T cells and CD4+CD57- T cells in BALF from most patients, while the expansion of other Vbeta T cells was also observed in some patients. Unexpectedly, the biased expansion of certain Vbeta T cells was also seen in either CD8+CD57+ T cells or CD8+CD57- T cells, while the expanded Vbeta T cells in CD8+ T cells differed substantially among individuals. BALF T cells showed a remarkably lower T cell receptor (TCR) intensity than that of peripheral blood T cells. Both CD8+ T cell subsets in BALF of sarcoidosis expressed the intracellular perforin/granzyme B, while all four subsets expressed intracellular IFN-gamma after in vitro activation, and CD4+ T cells, especially CD4+CD57+ T cells, expressed tumour necrosis factor-alpha. These findings indicate that CD57+ T cells as well as CD57- T cells in the BALF are phenotypically and functionally different from peripheral blood T cells and may play an important role in the Th1 dominant state and inflammation in pulmonary sarcoidosis.

Dendritic cells are responsible for the capacity of CpG oligodeoxynucleotides to act as an adjuvant for protective vaccine immunity against Leishmania major in mice

Vaccination with leishmanial Ag and CpG oligodeoxynucleotides (ODN) confers sustained cellular immunity and protection to infectious challenge up to 6 mo after immunization. To define the cellular mechanism by which CpG ODN mediate their adjuvant effects in vivo, the functional capacity of distinct dendritic cell (DC) subsets was assessed in the lymph nodes (LNs) of BALB/c mice, 36 h after immunization with the leishmanial antigen (LACK) and CpG ODN. After this immunization, there was a striking decrease in the frequency of the CD11c+B220+ plasmacytoid DCs with a proportionate increase in CD11c+CD8-B220- cells. CD11c+CD8+B220- cells were the most potent producers of interleukin (IL)-12 p70 and interferon (IFN)-gamma, while plasmacytoid DCs were the only subset capable of secreting IFN-alpha. In terms of antigen presenting capacity, plasmacytoid DCs were far less efficient compared with the other DC subsets. To certify that DCs were responsible for effective vaccination, we isolated CD11c+ and CD11c- cells 36 h after immunization and used such cells to elicit protective immunity after adoptive transfer in naive, Leishmania major susceptible BALB/c mice. CD11c+ cells but not 10-fold higher numbers of CD11c- cells from such immunized mice mediated protection. Therefore, the combination of LACK antigen and CpG ODN adjuvant leads to the presence of CD11c+ DCs in the draining LN that are capable of vaccinating naive mice in the absence of further antigen or adjuvant.

Interferon-producing cells fail to induce proliferation of naive T cells but can promote expansion and T helper 1 differentiation of antigen-experienced unpolarized T cells

Interferon-producing cells (IPCs) secrete high levels of type I interferon in response to certain viruses. The lack of lineage markers, the expression of major histocompatibility complex (MHC) class II and the capacity to stimulate allogeneic T cells have led these cells to be classified as a subset of dendritic cells (DCs), called plasmacytoid DCs (PDCs). However, the role of IPCs/PDCs in initiating primary immune responses remains elusive. Here we examined the antigen presenting capacity of murine IPCs in antigen specific systems. While CD8alpha+ and CD11b+ DCs induced logarithmic expansion of naive CD4 and CD8 T cells, without conferring T helper commitment at a first encounter, primary IPCs lacked the ability to stimulate naive T cells. However, when antigen-experienced, nonpolarized T cells expanded by classical DC subsets, were restimulated by IPCs, they proliferated and produced high amounts of IFN-gamma. These data indicate that IPCs can effectively stimulate preactivated or memory-type T cells and exert an immune-regulatory role. They also suggest that expansion of naive T cells and acquisition of effector function during antigen-specific T cell responses may involve different antigen-presenting cell (APC) types. Independent and coordinated control of T cell proliferation and differentiation would provide the immune system with greater flexibility in regulating immune responses.

Novel promiscuous HLA-DQ HIV Nef peptide that induces IFN-gamma-producing memory CD4+ T cells

We describe the highly conserved sequence 56-68 of the HIV Nef protein as the first promiscuous HLA-DQ HIV-derived peptide. The Nef peptide exhibits an albeit rare capacity to bind 6 different HLA-DQ molecules whereas no binding is observed with the 10 HLA-DR molecules tested. In agreement with these data, after immunization with the Nef peptide, HLA-DQ transgenic Abeta degrees mice display a vigorous cellular and humoral response while the specific immune response of HLA-DR expressing mice is minimal. The promiscuous potentiality of the Nef 56-68 peptide in humans has been confirmed by ex vivo immunization experiments with CD4+ T cells from 14 healthy donors expressing different HLA genotypes. Nef 56-68 specific CD4+ T cells rapidly acquire a memory cell phenotype and are characterized by the preferential usage of the TCR Vbeta 6.1 gene segment and predominant production of IFN-gamma. Taken together, these data indicate that the Nef 56-68 peptide constitutes an attractive component of vaccines aiming at inducing or enhancing HIV-specific T cell immunity.

A critical role for interleukin 18 in primary and memory effector responses to Listeria monocytogenes that extends beyond its effects on Interferon gamma production

The stimulation of interferon (IFN)-gamma by interleukin (IL)-12 has been shown to provide protection from intracellular pathogens such as Listeria monocytogenes. Tumor necrosis factor (TNF) is also a major player in the resolution of Listeria infections and is suggested to have more global effects than can be explained by the induction of IFN-gamma alone. Since IL-18 synergizes with IL-12 to induce IFN-gamma production by natural killer and T helper (Th)1 cells, we determined its role in responses to Listeria. IL-18 appeared to be even more potent than either IL-12 or IFN-gamma for protection against this pathogen and IL-18 enhanced bacterial clearance in the complete absence of IFN-gamma. Indeed IL-18 was comparable to TNF in its ability to resolve the infection and showed a lowered protective capacity in the absence of TNF. Moreover, IL-18 induced macrophages to secrete both TNF and nitric oxide after a Listeria infection. IL-18 was also essential for optimal IFN-gamma production by antigen-specific T cells. Therefore, IL-18 operates via its effects on both the innate immune response, including macrophages, as well as on Th1 cells, to protect against Listeria.

Anti-idiotype immunomodulation of experimental anti-phospholipid syndrome via effect on Th1/Th2 expression

Mice with experimental anti-phospholipid syndrome (APS), induced by active immunization with a human anti-cardiolipin MoAb (H-3), were treated with mouse anti-idiotypic MoAb (anti-H3, named S2.9) and with an irrelevant anti-idiotype. The immunized mice produced high titres of mouse anti-cardiolipin antibodies along with clinical manifestations of experimental APS: prolonged activated partial thromboplastin time (aPTT), thrombocytopenia and high rate of fetal loss. Treatment with the specific anti-Id (S2.9) as a whole molecule or F(ab)2 fraction, resulted in a decrease in serum levels of the anti-cardiolipin antibodies, rise in platelet count, shortened aPTT and reduced rate of fetal loss. The anti-Id effect was associated with a rise in the number of IL-2 and interferon-gamma (IFN-gamma)-secreting cells (Th1) and reduction in IL-4- and IL-6-secreting cells (Th2). The beneficial effect of the anti-Id treatment in mice with experimental APS induced by active immunization with an idiotype further supports the idiotypic aetiology of experimental APS and points to the role of Th1 cytokines in suppression of its manifestations.

Apoptosis of Th1-like cells in experimental tuberculosis (TB)

Th1 cell-induced anti-mycobacterial immunity is lost during a progressive Mycobacterium tuberculosis infection in a susceptible host. This study was designed to test the mechanism of the loss of anti-mycobacterial cell-mediated immune response. We demonstrate that M. tuberculosis infection results in increased Fas expression and decreased Bcl-2 expression in CD4+ T cells. When CD4+ T cells are stimulated in vitro, they show increased apoptosis and decreased production of IL-2 and interferon-gamma (IFN-gamma) but not of IL-4. These changes may result in selective apoptosis of Th1-like cells, leading to the loss of cell-mediated immune response against M. tuberculosis.

Nasal tolerance in experimental autoimmune myasthenia gravis (EAMG): induction of protective tolerance in primed animals

Nasal administration of microg doses of acetylcholine receptor (AChR) is effective in preventing the development of B cell-mediated EAMG in the Lewis rat, a model for human MG. In order to investigate whether nasal administration of AChR modulates ongoing EAMG, Lewis rats were treated nasally with AChR 2 weeks after immunization with AChR and Freund's complete adjuvant. Ten-fold higher amounts of AChR given nasally (600 microg/rat) were required to ameliorate the manifestations of EAMG compared with the amounts necessary for prevention of EAMG. In lymph node cells from rats receiving 600 microg/rat of AChR, AChR-induced proliferation and interferon-gamma (IFN-gamma) secretion were reduced compared with control EAMG rats receiving PBS only. The anti-AChR antibodies in rats treated nasally with 600 microg/rat of AChR had lower affinity, reduced proportion of IgG2b and reduced capacity to induce AChR degradation. Numbers of AChR-reactive IFN-gamma and tumour necrosis factor-alpha (TNF-alpha) mRNA-expressing lymph node cells from rats treated nasally with 600 microg/rat of AChR were suppressed, while IL-4, IL-10 and transforming growth factor-beta (TGF-beta) mRNA-expressing cells were not affected. Collectively, these data indicate that nasal administration of AChR in ongoing EAMG induced selective suppression of Th1 functions, i.e. IFN-gamma and IgG2b production, but no influence on Th2 cell functions. The impaired Th1 functions may result in the production of less myasthenic anti-AChR antibodies and contribute to the amelioration of EAMG severity in rats treated with AChR 600 microg/rat by the nasal route.

Genetic differences in immune reactivity to mercuric chloride (HgCl2): immunosuppression of H-2d mice is mediated by interferon-gamma (IFN-gamma)

Upon treatment with HgCl2, H-2s mice, such as B10.S, develop an activation of B lymphocytes that depends, at least partially, on activation of T helper type 2 (Th2) cells and results in increased serum levels of IgG1 and IgE, appearance of IgG autoantibodies, and development of immune glomerulonephritis and vasculitis. Results of previous studies and of experiments presented here indicate that the B cell activation and systemic autoimmune disease fail to develop in MHC-congenic B10.D2 (H-2d) and B10.BR (H-2k) mice treated with HgCl2, although B10.D2 T cells showed signs of activation by and specificity for HgCl2 comparable to those seen in strain B10.S. Here, we report that following HgCl2 injections the antibody response to sheep erythrocytes is normal in B10.S, but suppressed in B10.D2 mice. This suppression was prevented by MoAb to mouse IFN-gamma. Conversely, treatment of B10.D2 mice with murine recombinant IFN-gamma (rIFN-gamma) was able to reproduce the immunosuppression seen after HgCl2 treatment. In B10.S mice, it took administration of both rIFN-gamma and HgCl2 to suppress the anti-sheep erythrocyte response. Although rIFN-gamma diminished the increase in IgE serum levels of HgCl2-treated B10.S mice, it failed to prevent their autoantibody production and immune glomerulonephritis. These findings further strengthen the concept that B10.S mice react to HgCl2 by preferential activation of their Th2 cells producing IL-4, whereas B10.D2 mice react to HgCl2 by preferential activation of their Th1 cells, which produce IFN-gamma and thus suppress antibody responses.

Th1-like responses to peptides from peripheral nerve myelin proteins in patients with polyneuropathy associated with monoclonal gammopathy

Polyneuropathy associated with monoclonal gammopathy is usually regarded as an immune-mediated disorder with autoantibody activity against myelin glycoproteins. The pathogenic mechanisms are, however, not fully understood. Several reports have indicated an additional involvement of T cells. We investigated the occurrence of myelin-specific T cells as well as their functional characteristics. Cytokine responses generated after stimulation of peripheral blood mononuclear cells with selected peptides of myelin proteins P0 and P2 were investigated with an ELISPOT method. Three P0 peptides caused significantly elevated levels of interferon-gamma (IFN-gamma)-secreting cells in patients with polyneuropathy associated with monoclonal gammopathy (n = 8) compared with controls (n = 8), whereas none of the peptides caused elevated levels of IL-4-secreting cells. Patients with non-immunological types of neuropathy (n = 4) did not reveal any cytokine responses to myelin peptides. Our results indicate that a Th1-like response against myelin proteins occurs in polyneuropathy associated with monoclonal gammopathy.