Murine membranous nephropathy: immunization with α3(IV) collagen fragment induces subepithelial immune complexes and FcγR-independent nephrotic syndrome

Membranous nephropathy (MN) is a leading cause of nephrotic syndrome in adults and a significant cause of end-stage renal disease, yet current therapies are nonspecific, toxic, and often ineffective. The development of novel targeted therapies requires a detailed understanding of the pathogenic mechanisms, but progress is hampered by the lack of a robust mouse model of disease. We report that DBA/1 mice as well as congenic FcγRIII(-/-) and FcRγ(-/-) mice immunized with a fragment of α3(IV) collagen developed massive albuminuria and nephrotic syndrome, because of subepithelial deposits of mouse IgG and C3 with corresponding basement membrane reaction and podocyte foot process effacement. The clinical presentation and histopathologic findings were characteristic of MN. Although immunized mice produced genuine anti-α3NC1 autoantibodies that bound to kidney and lung basement membranes, neither crescentic glomerulonephritis nor alveolitis ensued, likely because of the predominance of mouse IgG1 over IgG2a and IgG2b autoantibodies. The ablation of activating IgG Fc receptors did not ameliorate injury, implicating subepithelial deposition of immune complexes and consequent complement activation as a major effector pathway. We have thus established an active model of murine MN. This model, leveraged by the availability of genetically engineered mice and mouse-specific reagents, will be instrumental in studying the pathogenesis of MN and evaluating the efficacy of novel experimental therapies.     

Resveratrol Possesses Protective Effects in a Pristane-Induced Lupus Mouse Model

Background

Systemic lupus erythematosus (SLE) is a multisystemic autoimmune disease characterized by the production of autoantibodies. To date, no therapy has been found to satisfactorily treat SLE. SIRT1 deficiency results in the development of an autoimmune syndrome in mice, including a high titer of anti-nuclear antibody in serum, immunoglobulin deposition in the kidney, and immune complex glomerulonephritis. Resveratrol is an activator of SIRT1 and possesses anti-inflammation and immune-regulatory properties.

Objective

To evaluate the preventative effects of resveratrol on a pristane-induced lupus animal model and assess its putative immune modulation effects.

Methods

BALB/c mice received a single intraperitoneal injection of 0.5 ml of pristane on day 1 and then various doses of resveratrol were given to the mice daily starting on day 2 and continuing for seven months. The autoantibodies in serum and supernatants were measured. Single cells isolated from spleen, isolated CD4+ T cells, and CD19+ B cells were cultured with or without resveratrol in vitro and assessed by flow cytometry.

Results

Resveratrol attenuated proteinuria, immunoglobuin depositon in kidney, and glomerulonephritis as well as IgG1 and IgG2a in serum in pristane-induced lupus mice. Resveratrol also suppressed CD69 and CD71 expression on CD4+ T cells as well as CD4+ T cell proliferation, induced CD4+ T cell apoptosis, and decreased CD4 IFNγ⁺ Th1 cells and the ratio of Th1/Th2 cells in vitro. In vitro antibody production and proliferation of B cells were also inhibited.

Conclusion

Resveratrol possesses protective effects in pristane-induced lupus mice and may represent a novel approach for the management of SLE.     

Granulocyte-colony stimulating factor treatment of lupus autoimmune disease in MRL-lpr/lpr mice.

G-CSF not only functions as an endogenous hemopoietic growth factor for neutrophils, but also displays pro-Th2 and antiinflammatory properties that could be of therapeutic benefit in autoimmune settings. We evaluated the effect of treatment with G-CSF in a murine model of spontaneous systemic lupus erythematosus, a disease in which G-CSF is already administered to patients to alleviate neutropenia, a common complication. Chronic treatment of lupus-prone MRL-lpr/lpr mice with low doses (10 microg/kg) of recombinant human G-CSF, despite the induction of a shift toward the Th2 phenotype of the autoimmune response, increased glomerular deposition of Igs and accelerated lupus disease. Conversely, high-dose (200 microg/kg) treatment with G-CSF induced substantial protection, prolonging survival by >2 mo. In the animals treated with these high doses of G-CSF, neither the Th1/Th2 profile nor the serum levels of TNF-alpha and IL-10 were modified. Despite the presence of immune complexes in their kidney glomeruli, no inflammation ensued, and serum IL-12 and soluble TNF receptors remained at pre-disease levels. This uncoupling of immune complex deposition and kidney damage resulted from a local down-modulation of FcgammaRIII (CD16) expression within the glomeruli by G-CSF. Our results demonstrate a beneficial effect of high doses of G-CSF in the prevention of lupus nephritis that may hold promise for future clinical applications, provided caution is taken in dose adjustment.     

Immunogene therapy of tumors with vaccine based on xenogeneic epidermal growth factor receptor

The breaking of immune tolerance against self epidermal growth factor receptor (EGFr) should be a useful approach for the treatment of receptor-positive tumors with active immunization. To test this concept, we constructed a plasmid DNA encoding extracellular domain of xenogeneic (human) EGFr (hEe-p) or corresponding control mouse EGFr (mEe-p) and empty vector (c-p). Mice immunized with hEe-p showed both protective and therapeutic antitumor activity against EGFr-positive tumor. Sera isolated from the hEe-p-immunized mice exhibited positive staining for EGFr-positive tumor cells in flow cytometric analysis and recognized a single 170-kDa band in Western blot analysis. Ig subclasses responded to rEGFr proteins were elevated in IgG1, Ig2a, and Ig2b. There was the deposition of IgG on the tumor cells. Adoptive transfer of the purified Igs showed the antitumor activity. The increased killing activity of CTL against EGFr-positive tumor cells could be blocked by anti-CD8 or anti-MHC class I mAb. In vivo depletion of CD4(+) T lymphocytes could completely abrogate the antitumor activity, whereas the depletion of CD8(+) cells showed partial abrogation. The adoptive transfer of CD4-depleted (CD8(+)) or CD8-depleted (CD4(+)) T lymphocytes isolated from mice immunized with hEe-p vaccine showed the antitumor activity. In addition, the increase in level of both IFN-gamma and IL-4 was found. Taken together, these findings may provide a new vaccine strategy for the treatment of EGFr-positive tumors through the induction of the autoimmune response against EGFr in a cross-reaction between the xenogeneic homologous and self EGFr.     

CD100 enhances dendritic cell and CD4+ cell activation leading to pathogenetic humoral responses and immune complex glomerulonephritis

CD100, a member of the semaphorin family, is a costimulatory molecule in adaptive immune responses by switching off CD72's negative signals. However, CD100's potential pathogenetic effects in damaging immune responses remain largely unexplored. We tested the hypothesis that CD100 plays a pathogenetic role in experimental immune complex glomerulonephritis. Daily injection of horse apoferritin for 14 days induced immune complex formation, mesangial proliferative glomerulonephritis and proteinuria in CD100-intact (CD100+/+) BALB/c mice. CD100-deficient (CD100-/-) mice were protected from histological and functional glomerular injury. They exhibited reduced deposition of Igs and C3 in glomeruli, reduced MCP-1 and MIP-2 intrarenal mRNA expression, and diminished glomerular macrophage accumulation. Attenuated glomerular injury was associated with decreased Ag-specific Ig production, reduced CD4+ cell activation and cytokine production. Following Ag injection, CD4+ cell CD100 expression was enhanced and dendritic cell CD86 expression was up-regulated. However, in CD100-/- mice, dendritic cell CD86 (but not CD80) up-regulation was significantly attenuated. Following i.p. immunization, CD86, but not CD80, promotes early Ag-specific TCR-transgenic DO11.10 CD4+ cell proliferation and IFN-gamma production, suggesting that CD100 expression enables full expression of CD86 and consequent CD4+ cell activation. Transfer of CD100+/+ DO11.10 cells into CD100-/- mice resulted in decreased proliferation demonstrating that CD100 from other sources in addition to CD100 from Ag-specific CD4+ cells plays a role in initial T cell proliferation. Although T cell-B cell interactions also may be relevant, these studies demonstrate that CD100 enhances pathogenetic humoral immune responses and promotes the activation of APCs by up-regulating CD86 expression.     

免疫共刺激分子OX40L对乙型肝炎核酸疫苗的免疫佐剂作用

[目的]为了进一步增强HBV DNA疫苗的免疫反应,本研究将共刺激分子OX40L 作为HBV DNA疫苗的分子佐剂免疫小鼠,旨在探讨共刺激分子OX40L对HBV DNA疫苗诱导体液和细胞免疫应答的影响.[方法]我们将HBV DNA疫苗(pcDS2)单独或联合共刺激分子质粒pOX40L免疫C57BL/6小鼠;分别在第0,2,4周进行免疫,在第6周检测抗-HBs IgG、IgG1和IgG2a,T淋巴细胞增殖指数,细胞因子表达水平和体内细胞毒性T淋巴细胞杀伤作用(CTL)等免疫学指标.[结果]pceDS2联合pOX40L免疫组小鼠的抗-HBs水平显著提高,抗-HBs IgG亚类以IgG2a占优;免疫小鼠的T淋巴细胞体外经乙型肝炎表面抗原(HBsAg)刺激后,联合免疫组刺激指数(SI)明显高于pcDS2组;联合免疫组CD4 + T淋巴细胞的IL-4和IFN-γ表达水平及CD8 + T淋巴细胞的IFN-γ表达水平显著升高;DNA疫苗免疫的各组小鼠,HBsAg特异性体内CTL高于对照组,其中联合免疫组小鼠的体内CTL杀伤作用最强.[结论]共刺激分子OX40L不仅能增强HBV DNA疫苗诱导特异性体液免疫应答,还能增强特异性细胞免疫反应,尤其增强体内CTL的杀伤活性,为HBV DNA疫苗的研究奠定了基础.     

Induction of IL-10-producing CD4+CD25+ T cells in animal model of collagen-induced arthritis by oral administration of type II collagen

Induction of oral tolerance has long been considered a promising approach to the treatment of chronic autoimmune diseases, including rheumatoid arthritis (RA). Oral administration of type II collagen (CII) has been proven to improve signs and symptoms in RA patients without troublesome toxicity. To investigate the mechanism of immune suppression mediated by orally administered antigen, we examined changes in serum IgG subtypes and T-cell proliferative responses to CII, and generation of IL-10-producing CD4+CD25+ T-cell subsets in an animal model of collagen-induced arthritis (CIA). We found that joint inflammation in CIA mice peaked at 5 weeks after primary immunization with CII, which was significantly less in mice tolerized by repeated oral feeding of CII before CIA induction. Mice that had been fed with CII also exhibited increased serum IgG1 and decreased serum IgG2a as compared with nontolerized CIA animals. The T-cell proliferative response to CII was suppressed in lymph nodes of tolerized mice also. Production of IL-10 and of transforming growth factor-beta from mononuclear lymphocytes was increased in the tolerized animals, and CD4+ T cells isolated from tolerized mice did not respond with induction of IFN-gamma when stimulated in vitro with CII. We also observed greater induction of IL-10-producing CD4+CD25+ subsets among CII-stimulated splenic T cells from tolerized mice. These data suggest that when these IL-10-producing CD4+CD25+ T cells encounter CII antigen in affected joints they become activated to exert an anti-inflammatory effect.     

Blockade of CTLA-4 signals inhibits Th2-mediated murine chronic graft-versus-host disease by an enhanced expansion of regulatory CD8+ T cells

CTLA-4 (CD152) is thought to be a negative regulator of T cell activation. Little is known about the function of CTLA-4 in Th2-type immune responses. We have investigated the effect of initial treatment with anti-CTLA-4 mAb on murine chronic graft-vs-host disease. Transfer of parental BALB/c splenocytes into C57BL/6 x BALB/c F1 mice induced serum IgE production, IL-4 expression by donor CD4+ T cells, and host allo-Ag-specific IgG1 production at 6-9 wk after transfer. Treatment with anti-CTLA-4 mAb for the initial 2 wk significantly reduced IgE and IgG1 production and IL-4 expression. Analysis of the splenic phenotype revealed the enhancement of donor T cell expansion, especially within the CD8 subset, and the elimination of host cells early after anti-CTLA-4 mAb treatment. This treatment did not affect early IFN-gamma expression by CD4+ and CD8+ T cells and anti-host cytolytic activity. Thus, blockade of CTLA-4 greatly enhanced CD8+ T cell expansion, and this may result in the regulation of consequent Th2-mediated humoral immune responses. These findings suggest a new approach for regulating IgE-mediated allergic immune responses by blockade of CTLA-4 during a critical period of Ag sensitization.     

Immunization of Aged Pigs with Attenuated Pseudorabies Virus Vaccine Combined with CpG Oligodeoxynucleotide Restores Defective Th1 Immune Responses

Background and Aims

Attempts to immunize aged subjects often result in the failure to elicit a protective immune response. Murine model studies have shown that oligonucleotides containing CpG motifs (CpG ODN) can stimulate immune system in aged mice as effectively as in young mice. Since many physiological and pathophysiological data of pigs can be transferred to humans, research in pigs is important to confirm murine data. Here we investigated whether immunization of aged pig model with attenuated pseudorabies virus vaccine (PRV vaccine) formulated with CpG ODN could promote a successful development of immune responses that were comparable to those induced in young pigs in a similar manner.

Methodology

Young and aged pigs were immunized IM with PRV vaccine alone, or in combination with CpG ODN respectively. At days 3, 7, 14 post immunization sera were assayed by ELISA for IgG titres, at day 7 for IgG1 and IgG2 subtypes titres. All blood samples collected in evacuated test tubes with K-EDTA at day 7 were analyzed for flow cytometer assay. Blood samples at day 7 collected in evacuated test tubes with heparin were analysed for antigen-specific cytokines production and peripheral blood mononuclear cells (PBMCs) proliferative responses.

Results

CpG ODN could enhance Th1 responses (PRV-specific IgG2/IgG1 ratio, proliferative responses, Th1 cytokines production) when used as an adjuvant for the vaccination of aged pigs, which were correlated with enhanced CD4+ T cells percentage, decreased CD4+CD8+CD45RO+ T cells percentage and improved PRV-specific CD4+ T cells activation.

Conclusions

Our results demonstrate a utility for CpG ODN, as a safe vaccine adjuvant for promoting effective systemic immune responses in aged pig model. This agent could have important clinical uses in overcoming some of age-associated depressions in immune function that occur in response to vaccination.     

Role of CD4+ and CD8+ T cells in murine resistance to street rabies virus.

Mice of the SJL/J and BALB/cByJ inbred strains are naturally resistant to street rabies virus (SRV) injected via the intraperitoneal route. To determine the cellular mechanism of resistance, monoclonal antibodies specific for CD4+ or CD8+ subsets of T cells were used to deplete the respective cell population in SRV-infected animals. Elimination of CD4+ T-helper cells abrogated the production of immunoglobulin G (IgG) neutralizing antibodies in response to rabies virus infection and reversed the resistant status of SJL/J and BALB/cByJ mice. In contrast, in vivo depletion of CD8+ cytotoxic T cells had no measurable effect on host resistance to SRV. These results indicate that serum neutralizing antibodies of the IgG class are a primary immunological mechanism of defense against rabies virus infection in this murine model of disease. CD8+ cytotoxic T lymphocytes, which have been shown to transfer protection in other rabies virus systems, appear to have no role in protecting mice against intraperitoneally injected SRV.     

Mechanisms of nasal tolerance induction in experimental autoimmune myasthenia gravis: identification of regulatory cells

Autoantigen administration via nasal mucosal tissue can induce systemic tolerance more effectively than oral administration in a number of experimental autoimmune diseases, including Ab-mediated experimental autoimmune myasthenia gravis, a murine model of myasthenia gravis. The mechanisms underlying nasal tolerance induction are not clear. In this study, we show that nasal administration of acetylcholine receptor (AChR) in C57BL/6 mice, before immunizations with AChR in adjuvant, results in delayed onset and reduced muscle weakness compared with control mice. The delayed onset and reduced muscle weakness were associated with decreased AChR-specific lymphocyte proliferation and decreased levels of anti-AChR Abs of the IgG2a and IgG2b isotypes in serum. The clinical and immunological changes in the AChR-pretreated C57BL/6 wild-type (wt) mice were comparable with those observed in AChR-pretreated CD8-/- mice, indicating that CD8+ T cells were not required for the generation of nasal tolerance. AChR-pretreated wt and CD8-/- mice showed augmented TGF-beta and reduced IFN-gamma responses, whereas levels of IL-4 were unaltered. Splenocytes from AChR-pretreated wt and CD8-/- mice, but not from CD4-/- mice, suppressed AChR-specific lymphocyte proliferation. This suppression could be blocked by Abs against TGF-beta. Thus, our results demonstrate that the suppression induced in the present model is independent of CD8+ T cells and suggest the involvement of Ag-specific CD4+ Th3 cells producing TGF-beta.     

Cationization of protein antigens. II. Alteration of regulatory properties

Immunoregulatory effects of cationized bovine serum albumin (cBSA) and native bovine serum albumin (nBSA) have been investigated. Intravenous administration of nBSA to BDF1 mice substantially suppressed the antibody response to subsequent immunization with either nBSA or cBSA, whereas pretreatment with cBSA by the same route significantly enhanced the responses to both antigens. The functional properties of BSA-specific T and B cells from mice immunized with cBSA or nBSA were examined in reconstitution experiments in which splenic T populations together with B cells were transferred into irradiated syngeneic recipients. Transfer of splenic T cells from mice primed with nBSA caused profound suppression of the response to subsequent immunization with nBSA or cBSA, whereas transfer of either B or T cells from cBSA treated mice produced an enhanced response to both antigens. C57BL/6 mice, which are considered to be low responders to BSA, produced a significant antibody response to BSA when immunized with cBSA. In contrast, immunization with nBSA did not produce measureable amounts of antibody in mice of this strain. Our data clearly demonstrate that cationized BSA exhibits unique immunogenic properties due to alterations in the self-regulation of the immune response.     

Analysis of the virus-specific and nonspecific B cell response to a persistent B-lymphotropic gammaherpesvirus

Respiratory challenge of mice with murine gammaherpesvirus 68 (gammaHV68) results in acute replication in respiratory epithelial cells and persistent, latent infection of B cells and macrophages. gammaHV68 elicits virus-specific Ab, and also nonspecifically activates B cells to Ab production through a CD4+ T cell-dependent process. The current analysis characterizes virus-specific and nonspecific Ab production at the single cell level and investigates the requirements and nature of the nonspecific response. Virus-specific Ab-forming cell (AFC) numbers were dwarfed by the increase in total AFC in all sites examined, indicating substantial nonspecific Ab production. Clear increases and decreases in specific and total AFC numbers occurred in the lymph nodes draining the respiratory tract and the spleen, but AFC numbers in the bone marrow (BM) increased to a plateau and remained constant. The longevity of the BM response was reflected in a sustained increase in virus-specific and total serum Ab levels. Generally, the IgG2a and IgG2b isotypes predominated. Analysis of cytokine-deficient mice, CD40 ligand-deficient mice, and radiation BM chimeras lacking MHC class II expression specifically on B cells indicated that nonspecific Ab production is independent of IL-6 or IFN-gamma, and dependent on cognate CD4+ T cell help. Several observations were consistent with polyclonal B cell activation by gammaHV68, including the induction of durable serum levels of IgG reactive with mammalian dsDNA and murine type II collagen. Our findings indicate new directions for studies of this valuable model of gamma-herpesvirus pathogenesis.     

Resveratrol Ameliorates Renal Damage,Increases Expression of Heme Oxygenase-1, and Has Anti-Complement,Anti-Oxidative,and Anti-Apoptotic Effects in a Murine Model of Membranous Nephropathy

BackgroundIdiopathic membranous nephropathy (MN) is an autoimmune-mediated glomerulonephritis and a common cause of nephrotic syndrome in adults. There are limited available treatments for MN. We assessed the efficacy of resveratrol (RSV) therapy for treatment of MN in a murine model of this disease.MethodsMurine MN was experimentally induced by daily subcutaneous administration of cationic bovine serum albumin, with phosphate-buffered saline used in control mice. MN mice were untreated or given RSV. Disease severity and pathogenesis was assessed by determination of metabolic and histopathology profiles, lymphocyte subsets, immunoglobulin production, oxidative stress, apoptosis, and production of heme oxygenase-1 (HO1).ResultsMN mice given RSV had significantly reduced proteinuria and a marked amelioration of glomerular lesions. RSV also significantly attenuated immunofluorescent staining of C3, although there were no changes of serum immunoglobulin levels or immunocomplex deposition in the kidneys. RSV treatment of MN mice also reduced the production of reactive oxygen species (ROS), reduced cell apoptosis, and upregulated heme oxygenase 1 (HO1). Inhibition of HO1 with tin protoporphyrin IX partially reversed the renoprotective effects of RSV. The HO1 induced by RSV maybe via Nrf2 signaling.ConclusionOur results show that RSV increased the expression of HO1 and ameliorated the effects of membranous nephropathy in a mouse model due to its anti-complement, anti-oxidative, and anti-apoptotic effects. RSV appears to have potential as a treatment for MN.     

Immunohistological characterization of leukocytes in the lungs of healthy mice and after bacterial intratracheal infection

Leukocytes in the peripheral lung parenchyma of mice have not been characterized histologically during bacterial infection. The aim of this study was to investigate (a) the immunohistological characteristics of healthy murine lungs and (b) the cell kinetics during acute inflammation. BALB/c and MF1 mice were examined; as well as transgenic mice with the gene defect of cystic fibrosis (CF) in the airways as an animal model for this disease. MF1 mice served as controls for the transgenic animals. Lavaged and perfused lungs were snap frozen. B and T lymphocytes, CD4+ and CD8+ cells, dendritic cells, neutrophils and a subset of macrophages were enumerated on cryostat lung sections. The lung tissue and bronchoalveolar lavage (BAL) of BALB/c mice, infected intratracheally with Haemophilus influenzae type b (Hib), were studied at different time points after infection. In the lungs of healthy mice, including CF mice, the largest population was that of T cells, CD4+ cells being always more frequent than CD8+ cells. During acute inflammation the number of neutrophils in the lung parenchyma and BAL increased strongly within the first hours after bacterial instillation and reached baseline levels within one week. This study provides a semi-quantitative analysis of immunocompetent cells in normal and infected murine lung tissue. Differences in cell numbers are found between different strains. Moreover, the cellular reaction during Hib infection in mouse lungs is dominated by neutrophils, as expected in a primary immune response. In uninfected CF mice the numbers and distribution of immune cells in the lung tissue are normal, indicating that the cellular defense is adequate.     

Circulating and tissue-bound immune complex formation in murine malaria.

Immune complex formation during Plasmodium berghei infection of OF1 mice was investigated. Circulating immune complexes (CIC) were detected by the Clg-binding assay and the conglutinin-binding solid-phase assay in lethal or drug-limited infections. CIC appeared on day 9 of infection, peaked on day 11, and disappeared only after complete cure of the infection. Analysis of the immune complexes detected by the Clq-binding assay revealed the following characteristics: sedimentation coefficients of 13S to 21S, resistance to DNAse, and selective removal by filtration through protein A bound to Sepharose. Glomerular deposits of IgM preceded the appearance of CIC, whereas deposits of IgG and C3 were concomitant with the appearance of CIC. Tissue-bound immunoglobulins were also found in the choroid plexus. The appearance of anti-malarial antibodies and malarial antigens in the serum was closely associated with a depression of C3 levels and the presence of CIC. Drug treatment was followed by normalization of C3 levels, and clearance of both CIC and malarial antigens.     

pConsensus peptide induces tolerogenic CD8+ T cells in lupus-prone (NZB x NZW)F1 mice by differentially regulating Foxp3 and PD1 molecules

Systemic lupus erythematosus is an autoimmune disease caused primarily by autoantibodies (including IgG anti-DNA) and immune complexes that cause tissue damage. After tolerization with an artificial peptide (pConsensus, pCons) based on murine anti-DNA IgG sequences containing MHC class I and class II T cell determinants, lupus-prone (NZB x NZW)F(1) female (BWF(1)) mice develop regulatory CD4+CD25+ T cells and inhibitory CD8+ T cells, both of which suppress anti-DNA Ig production and immune glomerulonephritis. In the present work, we show that splenocytes from BWF(1) mice treated with pCons had significant expansion of primarily CD8+ T cells. CD4+ T cells and B cells were each directly suppressed by CD8+ T cells from tolerized mice in a contact-independent manner. Both pCons-induced CD8+CD28+ and CD8+CD28- T cells suppressed production of anti-DNA in vitro. Silencing with small interfering RNA of Foxp3 abrogated the suppression mediated by both CD8+ T cell subsets. Additionally, CD8+ T cells from tolerized mice were weakly cytotoxic against syngeneic B cells from old anti-DNA-producing mice, but not from young mice. Importantly, pCons treatment had dual effects on CD8+ suppressor T cells from tolerized mice, increasing the intracellular expression of Foxp3 while decreasing the surface expression of PD1 molecules. Blocking PD1/PDL1 interactions in the CD8+ T cells from tolerized mice reduced their expression of Foxp3 and their ability to suppress CD4+CD25- proliferation. In contrast, blocking PD1/PDL1 in naive T cells increased Foxp3 expression. Our data suggest that tolerization with pCons activates different subsets of inhibitory/cytotoxic CD8+ T cells whose targets are both CD4+CD25- effector T cells and B cells.     

致死型夏氏疟原虫感染BALB/c小鼠CD4~＋ CD25~＋ Foxp3~＋调节性T细胞在Th2免疫应答极化中的作用研究

为探讨CD4＋ CD25＋ Foxp3＋调节性T细胞（Treg细胞）在疟疾感染过程中对Th2极化的调控作用,利用Treg细胞消除的致死型夏氏疟原虫（Plasmodium chabaudi chabaudi AS,P.c chabaudi AS）感染鼠疟模型进行研究。结果显示,对照组小鼠在感染后8 d原虫血症达到峰值40.5%,随后迅速下降,于感染后18 d小鼠自愈。相比,Treg细胞消除组于感染后10 d,原虫血症水平迅速上升至32%,随后小鼠相继死亡。在感染后8～10 d,Treg细胞消除小鼠脾脏CD4＋ CD25＋ Foxp3＋细胞占CD4＋细胞百分比含量明显低于对照组。同时,血清疟原虫特异性抗体IgG1和IgG2a水平均明显降低。结果提示,P.c chabaudi AS感染中CD4＋ CD25＋ Foxp3＋细胞参与调控Th2型免疫应答的极化,进而干预疟原虫清除。     

Protection of the villus epithelial cells of the small intestine from rotavirus infection does not require immunoglobulin A

Immunoglobulin A (IgA) is the primary immune response induced in the intestine by rotavirus infection, but vaccination with virus-like particles induces predominantly IgG, not IgA. To definitively assess the role of IgA in protection from rotavirus infection, IgA knockout mice, which are devoid of serum and secretory IgA, were infected and then rechallenged with murine rotavirus at either 6 weeks or 10 months. Following primary rotavirus infection, IgA knockout mice cleared virus as effectively as IgA normal control mice. Rotavirus-infected IgA knockout mice produced no serum or fecal IgA but did have high levels of antirotavirus serum IgG and IgM and fecal IgG, whereas IgA normal control mice made both serum IgA and IgG and fecal IgA. Both IgA normal and IgA knockout mice were totally protected from rotavirus challenge at 42 days. Ten months following a primary infection, both IgA normal and knockout mice still had high levels of serum and fecal antirotavirus antibody and were totally protected from rotavirus challenge. To determine if compensatory mechanisms other than IgG were responsible for protection from rotavirus infection in IgA knockout mice, mice were depleted of CD4(+) T cells or CD8(+) T cells. No changes in the level of protection were seen in depleted mice. These data show that fecal or systemic IgA is not essential for protection from rotavirus infection and suggest that in the absence of IgA, IgG may play a significant role in protection from mucosal pathogens.     

Role of murine Peyer's patch lymphocytes against primary and challenge infections with Cryptosporidium parvum

In order to determine the role of Peyeros patch lymphocytes (PPL) in self-clearing of Cryptosporidium parvum infection in murine models, changes in PPL subsets, their cytokine expression, and in vitro IgG1 and IgA secretions by PPL were observed in primary- and challenge-infected C57BL/6 mice. In primary-infected mice, the percentages of CD4+ T cells, CD8+ T cells, sIgA+ B cells, IL-2+ T cells, and IFN-gamma+ T cells among the PPL, increased significantly (P < 0.05) on day 10 post-infection (PI). Secretion of IgG1 and IgA in vitro by PPL also increased on day 10 PI. However, all these responses, with the exception of IgG1 and IgA secretions, decreased in challenge-infected mice on day 7 post-challenge (= day 13 PI); their IgG1 and IgA levels were higher (P > 0.05) than those in primaryinfected mice. The results suggest that murine PPL play an important role in self-clearing of primary C. parvum infections through proliferation of CD4+, CD8+, IL-2+, and IFN-gamma+ T cells, and IgG1 and IgA-secreting B cells. In challenge infections, the role of T cells is reduced whereas that of B cells secreting IgA appeared to be continuously important.