Real-time polymerase chain reaction analysis reveals an evolution of cytokine mRNA production in allograft acceptor mice

Modulation of inflammatory processes by thermal stimulating and RPE regenerative laser therapies in age related macular degeneration mouse models

Purpose

Inflammatory processes play a major role within the multifactorial pathogenesis of age-related macular degeneration (AMD). Neuroretina sparing laser therapies, thermal stimulation of the retina (TSR) and selective retina therapy (SRT), are known to reduce AMD-like pathology in vitro and in vivo. We investigated the effect of TSR and SRT on inflammatory processes in AMD mouse models.

Methods

One randomized eye of 8 months old apolipoprotein (Apo)E and 9 months old nuclear factor (erythroid-derived 2) -like 2 (NRF2) knock out mice were treated by TSR (10 ms, 532 nm, 50 µm² spot size, mean 4.5 W, ~200 spots) or SRT (~1.4 µs pulses, 532 nm, 50 µm spot size, 100 Hz over 300 ms, mean 2.5 µJ per pulse, ~200 spots). Fellow eyes, untreated knock out mice and wild-type BL/6J mice acted as controls. All mice were examined funduscopically and by optical coherence tomography (OCT) at the day of laser treatment. Mice were euthanized and enucleated either 1 day or 7 days after laser treatment and examined by gene expression analysis of 84 inflammatory genes.

Results

The inflammatory gene expression profile of both knock out models compared to healthy BL/6J mice suggests a regulation of pro- and anti-inflammatory processes especially concerning T-cell activity and immune cell recruitment. TSR resulted in downregulation of several pro-inflammatory cell-mediators both in ApoE -/- and NRF2-/- mice compared to treatment naïve litter mates one day after treatment. In contrast, SRT induced pro-inflammatory cell-mediators connected with necrosis one day after treatment as expected following laser-induced selective RPE cell death. Seven days after laser treatment, both findings were reversed.

Conclusions

Both TSR and SRT influence inflammatory processes in AMD mouse models. However, they act conversely. TSR leads to anti-inflammatory processes shortly after laser therapy and induces immune-cell recruitment one week after treatment. SRT leads to a quick inflammatory response to laser induced RPE necrotic processes. One week after SRT inflammation is inhibited. It remains unclear, if and to what extent this might play a role in a therapeutic or preventive approach of both laser modalities on AMD pathology.

Bifidobacterium breve and Streptococcus thermophilus Secretion Products Enhance T Helper 1 Immune Response and Intestinal Barrier in Mice

Lactic acid bacteria or their secretion products can modulate immune responses differently in normal and inflammatory conditions. This comparative study analyzes the effect of oral administration of living lactic acid bacteria, or their conditioned media, on the epithelial and immune functions of colitis-prone C57BL/6 IL-10-deficient mice. Mice were untreated (control) or infected with Helicobacter hepaticus with or without oral treatment with living bacteria, Bifidobacterium breve C50 and Streptococcus thermophilus 065 (LB), or their culture-conditioned media (CM). Histology, cytokine mRNA, electrical resistance, and barrier capacity of colonic samples as well as cytokine secretion by mesenteric lymph node (MLN) cells were studied. Helicobacter hepaticus mice developed only mild colitis, which was not modified in LB or CM groups. In the CM (but not the LB) group, the colonic barrier was reinforced as compared to the other groups, as evidenced by decreased horseradish peroxidase (HRP) transcytosis and mannitol fluxes and increased electrical resistance. In MLN, the percentage of CD4+ and CD8+ T cells secreting IFNγ was significantly higher in CM (2.06% and 1.98%, respectively) mice than in H. hepaticus (1–1% and 0.47%, P < 0.05) or control mice. In addition, the nonspecific stimulation of IFNγ, TNFΑ, and IL-12 secretion by MLN cells was significantly higher in the CM group as compared to the other groups. In the absence of severe colitis, Bifidobacterium breve C50- and Streptococcus thermophilus 065-conditioned media can reinforce intestinal barrier capacity and stimulate Th1 immune response, highlighting the involvement of lactic acid bacteria–derived components in host defense.

Effect of the TLR2/MyD88/NF-κB axis on corneal allograft rejection after penetrating keratoplasty

PURPOSE

To evaluate the effect of the TLR2 (Toll-like receptor 2)/MyD88/NF-κB axis on the allograft rejection after penetrating keratoplasty (PK).

METHODS

The PK rat models were randomly divided into four groups: allograft group, dexamethasone group, PDTC group and isograft group. The mean survival time (MST) and rejection index of corneal grafts were observed. The immunohistochemical staining of TGF-α was performed on day 15. The messenger RNA (mRNA) and protein expression of TLR2, MyD88 and NF-κB p65 in corneal grafts were detected by reverse transcription-polymerase chain reaction (RT-PCR) and western blotting.

RESULTS

On days 5, 7, 9, 11, 13 and 15, the rejection index in the allograft group was higher than in the other three groups (p < 0.05). The MST in the PDTC group (MST, 23.30 ± 0.42 days, n = 10) and in the dexamethasone group (MST, 24.40 ± 0.50 days, n = 10) were higher than in the allograft group (MST, 14.7 ± 0.70 days, n = 10) (χ(2) = 18.02, p < 0.01; χ(2) = 21.47, p < 0.01). The expression of TNF-α in the PDTC group and in the dexamethasone group decreased compared with the allograft group by immunohistochemistry. On day 15, the mRNA and protein expression of TLR2, MyD88 and NF-κB p65 in the PDTC group and the dexamethasone group were less than in the allograft group (p < 0.05).

CONCLUSIONS

Expression of TLR2, MyD88 and NF-κB p65 in rat corneal graft increased significantly and concurred with the allograft rejection, but were effectively inhibited by the treatment with dexamethasone and PDTC after PK. Dexamethasone could improve corneal allograft survival by the TLR2/MyD88/NF-κB axis. PDTC could suppress corneal graft rejection by inhibiting the activity of NF-κB. The TLR2/MyD88/NF-κB axis maybe a potential therapeutic target for corneal allograft rejection.

Pathogen recognition in the human female reproductive tract: expression of intracellular cytosolic sensors NOD1, NOD2, RIG-1, and MDA5 and response to HIV-1 and Neisseria gonorrhea

PROBLEM

Expression patterns and regulation of cytosolic pattern recognition receptors (PRR) NOD-1, NOD-2, RIG-1, and MDA5 have not been elucidated in the human female reproductive tract (FRT).

METHOD OF STUDY

Primary epithelial cells (EC) isolated from Fallopian tube (FT), endometrium (EM), cervix (Cx), and ectocervix (Ecx) were treated with estradiol, poly(I:C), Neisseria gonorrhea (GC), and HIV-1. PRR mRNA expressions were analyzed by Real-time RT-PCR. Conditioned media were analyzed for IL-8 by ELISA.

RESULTS

EC from all FRT compartments constitutively expressed NOD1, NOD2, RIG-1, and MDA5 with highest levels expressed by FT. Stimulation with poly(I:C) resulted in upregulation of NOD2, RIG-1, and MDA5 in all FRT compartments and correlated with increased secretion of IL-8, whereas estradiol treatment had no effects. Exposure to GC and HIV-1 IIIB but not BaL resulted in selective upregulation of NOD2 and MDA5.

CONCLUSION

PRR are expressed throughout the FRT and differentially regulated by poly(I:C), GC and HIV-1.

Mouse estrous cycle regulation of vaginal versus uterine cytokines, chemokines, α-/β-defensins and TLRs

This study investigates the cyclic changes in innate immunity in the female reproductive tract (FRT) of mice during the estrous cycle. By examining uterine and vaginal tissues and secretions we show that innate immunity varies with the stage of the estrous cycle and site in the FRT. Secretions from the uterine lumen contained cytokines and chemokines that were significantly higher at proestrus and estrus relative to that measured at diestrus. In contrast, analysis of vaginal secretions indicated that only IL-1β and CXCL1/mouse KC changed during the cycle, with highest levels measured at diestrus and estrus. In contrast, vaginal α-defensin 2 and β-defensins 1-4 mRNA levels peaked at proestrus and estrus and are expressed 1-4 logs greater than that seen in the uterus. These studies further indicate that TLR5 and TLR12 in the uterus, and TLR1, TLR2, TLR5 and TLR13 in the vagina varies with stage of the estrous cycle, with some peaking at proestrus/estrus and others at diestrus. Overall, these studies indicate that innate immune parameters in the uterus and vagina are separate and discrete, and regulated precisely during the estrous cycle.

The E3 ubiquitin ligase GRAIL regulates T cell tolerance and regulatory T cell function by mediating T cell receptor-CD3 degradation

T cell activation is tightly regulated to avoid autoimmunity. Gene related to anergy in lymphocytes (GRAIL, encoded by Rnf128) is an E3 ubiquitin ligase associated with T cell tolerance. Here, we generated and analyzed GRAIL-deficient mice and found they were resistant to immune tolerance induction and exhibited greater susceptibility to autoimmune diseases than wild-type mice. GRAIL-deficient naive T cells, after activation, exhibited increased proliferation and cytokine expression than controls and did not depend on costimulation for effector generation. Moreover, GRAIL-deficient regulatory T (Treg) cells displayed reduced suppressive function, associated with increased Th17 cell-related gene expression. GRAIL-deficient naive and Treg cells were less efficient in downregulating T cell receptor (TCR)-CD3 expression after activation and exhibited increased NFATc1 transcription factor expression; GRAIL expression promoted CD3 ubiquitinylation. Our results indicate that GRAIL, by mediating TCR-CD3 degradation, regulates naive T cell tolerance induction and Treg cell function.

Upregulation of the apoptosis-related inflammasome in cardiac allograft rejection

BACKGROUND

Inflammation is a major factor in cardiac allograft rejection. Accumulating reports have demonstrated an important role of the inflammation-induced adaptor complex, called the inflammasome, in the field of immunology. The apoptosis-associated, speck-like protein containing a caspase recruitment domain (ASC) is an adaptor protein that forms the inflammasome and regulates caspase-1-dependent generation of inflammatory cytokines. The aim of the present study was to determine how ASC is associated with the development of cardiac allograft rejection.

METHODS

We used a murine heterotopic cardiac transplantation model between fully incompatible strains. Donor hearts (n = 9 for each time-point) were harvested for examination on Days 1, 4, 7 and 12 after transplantation. Histopathologic findings of cardiac grafts were evaluated using rejection scores. The expression of ASC and inflammatory cytokines in cardiac grafts were analyzed by immunohistochemistry and real-time reverse transcript-polymerase chain reaction (RT-PCR).

RESULTS

Expression levels of both ASC and IL-1 beta were higher in the myocardial interstitium of allografts in parallel to the progress of cardiac rejection during the acute phase after transplantation. In contrast, expression of ASC and IL-1 beta remained low in isografts. Cardiac allografts treated with tacrolimus showed decreased expression of both ASC and IL-1 beta similar to that seen in isografts. Real-time RT-PCR demonstrated similar alteration of ASC and IL-1 beta mRNA expression in cardiac grafts during the acute phase.

CONCLUSIONS

Our results demonstrate a novel finding showing that upregulation of ASC is closely associated with the inflammation induced in cardiac grafts after transplantation in the mouse.

RETRACTED: Chronic cardiac allograft rejection in mice is alleviated by inhibition of CCR5 in combination with cyclosporine A

The chemokine receptor CCR5 plays important roles in acute allograft rejection. In this study, we examined the inhibition of CCR5 in combination with the treatment with cyclosporine A (CsA) in chronic rejection in cardiac transplantation. Forty-five transplant recipients were randomized to three groups. Recipients in group A were treated with anti-CCR5 mAb and CsA, mice in group B were given anti-CCR5 mAb alone, and animals in group C were administered with only CsA. On day 45 after transplantation, the allografts were harvested and examined by immunohistologic technique and PT-PCR methods. Allografts treated with anti-CCR5 mAb and CsA showed significantly prolonged survival (44.73 ± 0.258 days, P < 0.01) as compared with CsA-treated group (37.00 ± 2.04 days). Treatment with anti-CCR5 mAb plus CsA significantly inhibited the progression of cardiac allograft vasculopathy. Our findings demonstrated that anti-CCR5 mAb in combination with CsA can prolong the survival of allograft through their cardio-protective and immunomodulative properties. Thus, combined administration of anti-CCR5 mAb and CsA may become a new therapeutic approach for the prevention of cardiac graft failure that has not been obviated by conventional immunosuppressive agents.

Gnotobiotic mouse immune response induced by Bifidobacterium sp. strains isolated from infants

Bifidobacterium, which is a dominant genus in infants' fecal flora and can be used as a probiotic, has shown beneficial effects in various pathologies, including allergic diseases, but its role in immunity has so far been little known. Numerous studies have shown the crucial role of the initial intestinal colonization in the development of the intestinal immune system, and bifidobacteria could play a major role in this process. For a better understanding of the effect of Bifidobacterium on the immune system, we aimed at determining the impact of Bifidobacterium on the T-helper 1 (T(H)1)/T(H)2 balance by using gnotobiotic mice. Germfree mice were inoculated with Bifidobacterium longum NCC2705, whose genome is sequenced, and with nine Bifidobacterium strains isolated from infants' fecal flora. Five days after inoculation, mice were killed. Transforming growth factor beta1 (TGF-beta1), interleukin-4 (IL-4), IL-10, and gamma interferon (IFN-gamma) gene expressions in the ileum and IFN-gamma, tumor necrosis factor alpha (TNF-alpha), IL-10, IL-4, and IL-5 secretions by splenocytes cultivated for 48 h with concanavalin A were quantified. Two Bifidobacterium species had no effect (B. adolescentis) or little effect (B. breve) on the immune system. Bifidobacterium bifidum, Bifidobacterium dentium, and one B. longum strain induced T(H)1 and T(H)2 cytokines at the systemic and intestinal levels. One B. longum strain induced a T(H)2 orientation with high levels of IL-4 and IL-10, both secreted by splenocytes, and of TGF-beta gene expression in the ileum. The other two strains induced T(H)1 orientations with high levels of IFN-gamma and TNF-alpha splenocyte secretions. Bifidobacterium's capacity to stimulate immunity is species specific, but its influence on the orientation of the immune system is strain specific.

Requirement of MyD88 for macrophage-mediated islet xenograft rejection after adoptive transfer

BACKGROUND

Porcine antigen primed and CD4+ T-cell activated macrophages are able to migrate to and destroy porcine xenografts. However, the specific signaling mechanisms involved remain to be identified.

METHODS

In this study macrophages which lack the universal toll-like receptor (TLR) adaptor MyD88 were used to investigate the role of TLR in the recognition and activation of macrophages in islet xenograft rejection. Macrophages were isolated from rejecting MyD88(-/-) and wild-type C57BL/6 mice that were recipients of neonatal porcine pancreatic cell cluster (NPCC) xenografts, and were transferred to NPCC recipient NOD-SCID mice.

RESULTS

Both wild-type C57BL/6 and MyD88(-/-) mice rejected NPCC xenografts 8 and 10 days, respectively after transplantation, and the grafts were heavily infiltrated with CD4+ T cells and macrophages. However, graft infiltrating macrophages from rejecting MyD88(-/-) recipients demonstrated impaired up-regulation of TLR expression and impaired activation phenotype, when compared to those from rejecting C57BL/6 recipients. Transfer of NOD-SCID recipients with macrophages from rejecting C57BL/6 mice resulted in NPCC xenograft rejection along with massively infiltrated macrophages 8 days after transfer, whereas NPCC xenografts in NOD-SCID mice transferred with macrophages from rejecting MyD88(-/-) mice remained intact until the end of this study, 90 days after transfer, with insulin-positive islets and no infiltration by macrophages.

CONCLUSION

This study demonstrates that deletion of MyD88 causes impaired macrophage activation after pig islet xenotransplantation. However, graft survival is not prolonged and xenografts are rejected rapidly by alternate mechanisms.

Inhibition of arginase I activity by RNA interference attenuates IL-13-induced airways hyperresponsiveness

Increased arginase I activity is associated with allergic disorders such as asthma. How arginase I contributes to and is regulated by allergic inflammatory processes remains unknown. CD4+ Th2 lymphocytes (Th2 cells) and IL-13 are two crucial immune regulators that use STAT6-dependent pathways to induce allergic airways inflammation and enhanced airways responsiveness to spasmogens (airways hyperresponsiveness (AHR)). This pathway is also used to activate arginase I in isolated cells and in hepatic infection with helminths. In the present study, we show that arginase I expression is also regulated in the lung in a STAT6-dependent manner by Th2-induced allergic inflammation or by IL-13 alone. IL-13-induced expression of arginase I correlated directly with increased synthesis of urea and with reduced synthesis of NO. Expression of arginase I, but not eosinophilia or mucus hypersecretion, temporally correlated with the development, persistence, and resolution of IL-13-induced AHR. Pharmacological supplementation with l-arginine or with NO donors amplified or attenuated IL-13-induced AHR, respectively. Moreover, inducing loss of function of arginase I specifically in the lung by using RNA interference abrogated the development of IL-13-induced AHR. These data suggest an important role for metabolism of l-arginine by arginase I in the modulation of IL-13-induced AHR and identify a potential pathway distal to cytokine receptor interactions for the control of IL-13-mediated bronchoconstriction in asthma.

Stimulation of immunity without alteration of oral tolerance in mice fed with heat-treated fermented infant formula

OBJECTIVES

Little information is available on the properties of fermented milk formula intended to healthy infants. This study analyzes the effect of long-term ingestion of a heat-treated, fermented milk formula on the development of oral tolerance or systemic immune response to soluble antigens in mice.

MATERIALS AND METHODS

The C3H/HeN mice, fed with a heat-treated fermented (Bifidobacterium breve C50 and Streptococcus thermophilus 065) infant formula (htFF) or a matched control diet (control), were immunized with ovalbumin (OVA) with or without gavage of 20 mg OVA to induce tolerance or immunity, respectively. Systemic and local anti-OVA immune responses and intestinal barrier function were measured after 5 to 6 weeks.

RESULTS

Oral tolerance to OVA developed similarly in htFF- and control-fed mice, attested to by the downregulation of OVA-specific immunoglobulin (Ig) G and IgE after oral OVA administration. In contrast, immunization with OVA led to significantly higher titers in htFF-fed mice than in control-fed mice (log2 IgG titers, 16.45 +/- 1.24 and 15.46 +/- 0.79, respectively; P = 0.012). Jejunal interferon gamma, interleukin 12p40 and interleukin 10 expressions were significantly higher in tolerized mice fed with htFF compared with those fed with the control diet. Mucosal to serosal intact horseradish peroxidase fluxes were lower in htFF-fed mice than in control-fed mice (39 +/- 8 and 118 +/- 38 ng/h x cm2, respectively; P < 0.0001), indicating that the htFF diet reinforces intestinal barrier capacity to macromolecules.

CONCLUSIONS

In mice, htFF strengthens intestinal barrier and enhances systemic immune responses to antigens without interfering with the development of oral tolerance, suggesting a potential beneficial effect in host defence and vaccination.

Fcgamma receptor-ligating complexes improve the course of experimental autoimmune encephalomyelitis by enhancing basal Th2 responses

IL-12p40 and macrophages are essential for the induction of disease in the mouse model of multiple sclerosis, experimental autoimmune encephalomyelitis. In this paper, we show that treatment of mice with opsonized erythrocytes, which have been shown to ligate Fcgamma receptors on macrophages and alter their cytokine profile, significantly delayed the onset of experimental autoimmune encephalomyelitis. This protection correlated to the induction of Th2 responses by autoreactive T cells, enhanced basal systemic responses and a significant downregulation of IL-12p40 and nitric oxide synthase-2, but not IFN-gamma expression. IL-4 was essential for the protection by opsonized erythrocytes as the effects of treatment were eliminated in IL-4-deficient mice. Together these studies suggest that the ligation of Fcgamma receptors can modify the development of autoimmune disease by altering macrophage activation and enhancing Th2 responses.

Comparison of intranasal and transcutaneous immunization for induction of protective immunity against Chlamydia muridarum respiratory tract infection

Chlamydia pneumoniae causes a range of respiratory infections including bronchitis, pharyngitis and pneumonia. Infection has also been implicated in exacerbation/initiation of asthma and chronic obstructive pulmonary disease (COPD) and may play a role in atherosclerosis and Alzheimer's disease. We have used a mouse model of Chlamydia respiratory infection to determine the effectiveness of intranasal (IN) and transcutaneous immunization (TCI) to prevent Chlamydia lung infection. Female BALB/c mice were immunized with chlamydial major outer membrane protein (MOMP) mixed with cholera toxin and CpG oligodeoxynucleotide adjuvants by either the IN or TCI routes. Serum and bronchoalveolar lavage (BAL) were collected for antibody analysis. Mononuclear cells from lung-draining lymph nodes were stimulated in vitro with MOMP and cytokine mRNA production determined by real time PCR. Animals were challenged with live Chlamydia and weighed daily following challenge. At day 10 (the peak of infection) animals were sacrificed and the numbers of recoverable Chlamydia in lungs determined by real time PCR. MOMP-specific antibody-secreting cells in lung tissues were also determined at day 10 post-infection. Both IN and TCI protected animals against weight loss compared to non-immunized controls with both immunized groups gaining weight by day 10-post challenge while controls had lost 6% of body weight. Both immunization protocols induced MOMP-specific IgG in serum and BAL while only IN immunization induced MOMP-specific IgA in BAL. Both immunization routes resulted in high numbers of MOMP-specific antibody-secreting cells in lung tissues (IN>TCI). Following in vitro re-stimulation of lung-draining lymph node cells with MOMP; IFNgamma mRNA increased 20-fold in cells from IN immunized animals (compared to non-immunized controls) while IFNgamma levels increased 6- to 7-fold in TCI animals. Ten days post challenge non-immunized animals had >7,000 IFU in their lungs, IN immunized animals <50 IFU and TCI immunized animals <1,500 IFU. Thus, both intranasal and transcutaneous immunization protected mice against respiratory challenge with Chlamydia. The best protection was obtained following IN immunization and correlated with IFNgamma production by mononuclear cells in lung-draining LN and MOMP-specific IgA in BAL.

Transport of IgG across the blood-luminal barrier of the male reproductive tract of the rat and the effect of estradiol administration on reabsorption of fluid and IgG by the epididymal ducts

In rats immunized systemically with tetanus toxoid the concentration of specific anti-tetanus-toxoid-specific IgG in fluid from the rete testis and cauda epididymidis were respectively 0.6% and 1.4% the concentration in blood serum. The extratesticular duct system reabsorbed 97% of the IgG and 99% of the fluid leaving the rete, but estradiol administration affected the site of reabsorption. In untreated rats, the ductuli efferentes reabsorbed 94% of the IgG and 96% of the fluid leaving the rete, whereas estradiol-treated rats reabsorbed 83% of the IgG and 86% of the fluid, and the ductus epididymidis fully compensated for these different effects of estradiol on the ductuli efferentes. The concentrations of IgG in secretions of the seminal vesicles and prostate gland were lower (0.1% and 0.3% respectively of the titers in blood serum) than in fluids from the extratesticular ducts, and were not affected by the administration of estradiol. RT-PCR showed that Fcgrt (neonatal Fc receptor, also known as FcRn) is expressed in the reproductive ducts, where IgG is probably transported across epithelium, being particularly strong in the ductuli efferentes (where most IgG was reabsorbed) and distal caput epididymidis. It is concluded that IgG enters the rete testis and is concentrated only 2.5-fold along the extratesticular duct system, unlike spermatozoa, which are concentrated 95-fold. Further, the ductus epididymidis can recognize and compensate for changes in function of the ductuli efferentes.

Direct Regulatory Role of NKT Cells in Allogeneic Graft Survival Is Dependent on the Quantitative Strength of Antigenicity

The role of NKT cells during immune responses is diverse, ranging from antiviral and antitumor activity to the regulation of autoimmune diseases; however, the regulatory function of CD1d-dependent NKT cells in rejection responses against allogeneic graft is uncertain. In this study, we demonstrated the direct regulatory effects of CD1d-dependent NKT cells using an allogeneic skin transplantation model. H-Y-mismatched skin graft survival was shortened in CD1d-/- recipients compared with wild-type recipients. Adoptive transfer of syngeneic NKT cells via splenocytes or hepatic mononuclear cells into CD1d-/- recipients restored graft survival times to those of wild-type recipients. alpha-Galactosylceramide, a specific activator of NKT cells, further prolonged graft survival. Although CD1d-dependent NKT cells did not extend skin graft survival in either major or complete minor histocompatibility-mismatched models, these cells affected graft survival in minor Ag mismatch models according to the magnitude of the antigenic difference. The afferent arm of NKT cell activation during transplantation required CD1d molecules expressed on host APCs and the migration of CD1d-dependent NKT cells into grafts. Moreover, the regulatory effects of CD1d-dependent NKT cells against alloantigen were primarily IL-10 dependent. Taken together, we concluded that CD1d-dependent NKT cells may directly affect the outcome of allogeneic skin graft through an IL-10-dependent regulatory mechanism.

T-cell autoreactivity to Hsp in human transplantation may involve both proinflammatory and regulatory functions

Heat shock proteins (Hsp) are moving from the category of basically intracellular chaperone molecules to important proteins in both innate and acquired immune responses, with great potential for clinical application as immunomodulators. Both proinflammatory and regulatory Hsp-reactive T cells have been described in animal models of autoimmune diseases. To investigate the role of autoreactivity to Hsp60 and Hsp70 in human transplantation, we analyzed, sequentially, peripheral blood mononuclear cell proliferation and cytokine production before and at different time points after renal transplantation, as well as the modulation of proliferation to Hsp in the presence of exogenous cytokines. Proliferation to Hsp60 and Hsp70 in the pretransplantation (pre-Tx) period was significantly associated with rejection episodes in the first months post-Tx. In contrast, IL-4 production was significantly associated with absence of rejection. Addition of exogenous IL-4 distinctly modulated the proliferative response to Hsp60; inhibiting proliferation in 83% of patients in the early post-Tx period (0-6 months), in which rejection episodes occurred, and inducing proliferation in 62.5% of patients in the later period (>12-24 months), when no rejection was observed. Characterization of autoreactive anti-Hsp60 regulatory T cells may permit new approaches to control the proinflammatory response to the graft, as well as aggressive autoimmunity.

Suppression of Acute and Chronic Rejection by Hepatocyte Growth Factor in a Murine Model of Cardiac Transplantation

Background— Although treatment with immunosuppressive agents has contributed to overcoming acute rejection and improving the midterm survival of transplanted hearts, cardiac allograft vasculopathy (CAV) has remained the main cause of primary graft failure. Recent approaches have shown that hepatocyte growth factor (HGF) exhibits cardiotrophic functions. We therefore addressed whether HGF would regulate acute and chronic rejection in cardiac transplantation.

Methods and Results— We used a murine heterotopic cardiac transplantation model between fully incompatible strains and administered 500 μg · kg −1 · d −1 HGF during the initial 14 days after transplantation. The HGF-treated allografts showed significantly prolonged survival (42.3±4.1 days, P <0.001) compared with the controls (11.1±0.6 days), with tolerance induction in 47.4%. Histopathologically, the number of infiltrating cells was significantly decreased and myocardial necrosis was less prominent with a reduction of apoptosis in the allografts by HGF treatment during acute rejection. In the long-term surviving allografts, HGF significantly inhibited the development of CAV and interstitial fibrosis. With respect to intragraft cytokine mRNA expression, HGF treatment reduced the early expression of interferon-γ and enhanced the expression of transforming growth factor-β1 during the acute phase and of interleukin-10 continuously through the acute phase to the chronic phase.

Conclusions— Our findings demonstrate that HGF can prolong the survival of allografts by its cardioprotective and immunomodulative potencies. Thus, HGF administration may constitute a new therapeutic approach to preventing cardiac graft failure that has not been overcome by conventional immunosuppressive agents.

Short-term peaks in glucose promote renal fibrogenesis independently of total glucose exposure

Postprandial hyperglycemia is implicated as a risk factor predisposing to vascular complications. This study was designed to assess recurrent short-term increases in glucose on markers of renal fibrogenesis. Human renal cortical fibroblasts were exposed to fluctuating short-term (2 h) increases to 15 mM d-glucose, three times a day over 72 h, on a background of 5 mM d-glucose. To determine whether observed changes were due to fluctuating osmolality, identical experiments were undertaken with cells exposed to l-glucose. Parallel experiments were performed in cells exposed to 5 mM d-glucose and constant exposure to either 15 or 7.5 mM d-glucose. Fluctuating d-glucose increased extracellular matrix, as measured by proline incorporation (P < 0.05), collagen IV (P < 0.005), and fibronectin production (P < 0.001), in association with increased tissue inhibitor of matrix metalloproteinase (MMP) (P < 0.05). Sustained exposure to 15 mM d-glucose increased fibronectin (P < 0.001), in association with increased MMP-2 (P = 0.01) and MMP-9 activity (P < 0.05), suggestive of a protective effect on collagen matrix accumulation. Transforming growth factor-beta(1) (TGF-beta(1)) mRNA was increased after short-term (90 min) exposure to 15 mM glucose (P < 0.05) and after 24-h exposure to 7.5 mM ? (P < 0.05). Normalization of TGF-beta(1) secretion occurred within 48 h of constant exposure to an elevated glucose. Fluctuating l-glucose also induced TGF-beta(1) mRNA and a profibrotic profile, however, to a lesser extent than observed with exposure to fluctuating d-glucose. The results suggest that exposure to fluctuating glucose concentrations increases renal interstitial fibrosis compared with stable elevations in d-glucose. The effects are, in part, due to the inherent osmotic changes.

Immunization with a DNA vaccine cocktail protects mice lacking CD4 cells against an aerogenic infection with Mycobacterium tuberculosis

Tuberculosis (TB) is the most common opportunistic disease and a potentially fatal complication among immunocompromised individuals infected with human immunodeficiency virus (HIV). Effective vaccination against TB in persons with HIV has been considered unlikely because of the central role that CD4 cells play in controlling tuberculous infections. Here we show that the vaccination of CD8(-/-) mice with a TB DNA vaccine cocktail did not significantly enhance protective responses to a Mycobacterium tuberculosis infection. In contrast, immunization with a DNA vaccine cocktail or with the current TB vaccine, Mycobacterium bovis BCG, induced considerable antituberculosis protective immunity in immune-deficient mice lacking CD4 cells. In vaccinated CD4(-/-) animals, substantially reduced bacterial burdens in organs and much improved lung pathology were seen 1 month after an aerogenic M. tuberculosis challenge. Importantly, the postchallenge mean times to death of vaccinated CD4(-/-) mice were significantly extended (mean with DNA cocktail, 172 +/- 7 days; mean with BCG, 156 +/- 22 days) compared to that of naïve CD4(-/-) mice (33 +/- 6 days). Furthermore, the treatment of DNA-vaccinated CD4(-/-) mice with an anti-CD8 or anti-gamma interferon (IFN-gamma) antibody significantly reduced the effect of immunization, and neither IFN-gamma(-/-) nor tumor necrosis factor receptor-deficient mice were protected by DNA immunization; therefore, the primary vaccine-induced protective mechanism in these immune-deficient mice likely involves the secretion of cytokines from activated CD8 cells. The substantial CD8-mediated protective immunity that was generated in the absence of CD4 cells suggests that it may be possible to develop effective TB vaccines for use in HIV-infected populations.

Transcutaneous immunization with combined cholera toxin and CpG adjuvant protects against Chlamydia muridarum genital tract infection

Chlamydia trachomatis is a pathogen of the genital tract and ocular epithelium. Infection is established by the binding of the metabolically inert elementary body (EB) to epithelial cells. These are taken up by endocytosis into a membrane-bound vesicle termed an inclusion. The inclusion avoids fusion with host lysosomes, and the EBs differentiate into the metabolically active reticulate body (RB), which replicates by binary fission within the protected environment of the inclusion. During the extracellular EB stage of the C. trachomatis life cycle, antibody present in genital tract or ocular secretions can inhibit infection both in vivo and in tissue culture. The RB, residing within the intracellular inclusion, is not accessible to antibody, and resolution of infection at this stage requires a cell-mediated immune response mediated by gamma interferon-secreting Th1 cells. Thus, an ideal vaccine to protect against C. trachomatis genital tract infection should induce both antibody (immunoglobulin A [IgA] and IgG) responses in mucosal secretions to prevent infection by chlamydial EB and a strong Th1 response to limit ascending infection to the uterus and fallopian tubes. In the present study we show that transcutaneous immunization with major outer membrane protein (MOMP) in combination with both cholera toxin and CpG oligodeoxynucleotides elicits MOMP-specific IgG and IgA in vaginal and uterine lavage fluid, MOMP-specific IgG in serum, and gamma interferon-secreting T cells in reproductive tract-draining caudal and lumbar lymph nodes. This immunization protocol resulted in enhanced clearance of C. muridarum (C. trachomatis, mouse pneumonitis strain) following intravaginal challenge of BALB/c mice.

Widespread bronchogenic dissemination makes DBA/2 mice more susceptible than C57BL/6 mice to experimental aerosol infection with Mycobacterium tuberculosis

We have used the murine model of aerosol-induced experimental tuberculosis to assess the effects of four clinical isolates and a reference strain of Mycobacterium tuberculosis on resistant C57BL/6 mice and susceptible DBA/2 mice. Histological studies and detection of 25 cytokines potentially involved in the infection were carried out. DBA/2 mice showed higher concentrations of bacilli in bronchoalveolar lavage fluid and lung tissue. Furthermore, these mice evidenced a larger granulomatous infiltration in the parenchyma due to an increased rate of emigration of infected foamy macrophages from the granulomas to the neighboring pulmonary alveolar spaces. The better control of bacillary concentrations and pulmonary infiltration observed in C57BL/6 mice from week 3 postinfection could result from their higher RANTES, ICAM-1, and gamma interferon (IFN-gamma) mRNA levels. On the other hand, the higher MIP-2 and MCP-3 mRNA levels seen in DBA/2 mice would result in stronger lung recruitment of macrophages and neutrophils. Additionally, DBA/2 mice showed increased inducible nitric oxide synthase expression, induced by the larger number of foamy macrophages, at weeks 18 and 22. This increment was a consequence of phagocytosed bacillary debris, was independent of IFN-gamma expression, and could exert only a bacteriostatic effect. The results of the study suggest that DBA/2 mice are more susceptible than C57BL/6 mice to M. tuberculosis infection due to a higher bronchial dissemination of bacilli inside poorly activated foamy macrophages.

Schistosomiasis decreases central nervous system inflammation and alters the progression of experimental autoimmune encephalomyelitis

A preestablished infection with the parasitic helminth, Schistosoma mansoni, significantly reduced the incidence and delayed the onset of experimental autoimmune encephalomyelitis (EAE) in C57BL/6J mice immunized with myelin oligodendrocyte glycoprotein (MOG)(35-55) peptide. The altered disease progression was not solely due to the induction of a strong Th2 response, since intraperitoneal injection of schistosome eggs did not affect disease development. MOG-specific gamma interferon (IFN-gamma), nitric oxide, and tumor necrosis factor alpha production by splenocytes was significantly reduced in schistosome-infected mice compared to uninfected mice. However, similar levels of interleukin-10 (IL-10) were produced in an antigen-specific manner, suggesting that the induction of antigen-specific responses was not inhibited. Analysis of in vivo cytokine production by real-time PCR indicated that IL-12p40, but not IFN-gamma, transcript levels were dramatically reduced in the spinal cords of schistosome-infected, MOG-immunized mice. Furthermore, analysis of the cellular composition of the spinal cords and brains revealed that a preestablished infection with S. mansoni decreased central nervous system (CNS) inflammation, particularly of macrophages and CD4 T cells. These results suggest that schistosomiasis may negatively regulate the onset of EAE by downregulating the production of proinflammatory cytokines and altering CNS inflammation.

Critical role of the Toll-like receptor signal adaptor protein MyD88 in acute allograft rejection

The Toll-like receptors (TLRs) are recently discovered germline-encoded receptors on APCs that are critically important in innate immune recognition of microbial pathogens. However, their role in solid-organ transplantation is unknown. To explore this role, we employed a skin allograft model using mice with targeted deletion of the universal TLR signal adaptor protein, MyD88. We report that minor antigen-mismatched (HY-mismatched) allograft rejection cannot occur in the absence of MyD88 signaling. Furthermore, we show that the inability to reject these allografts results from a reduced number of mature DCs in draining lymph nodes, leading to impaired generation of anti-graft-reactive T cells and impaired Th1 immunity. Hence, this work demonstrates that TLRs can be activated in a transplant setting and not solely by infections. These results link innate immunity to the initiation of the adaptive alloimmune response.

Cytokine expression in respiratory syncytial virus-infected mice as measured by quantitative reverse-transcriptase PCR

In the murine model for respiratory syncytial virus (RSV) infection, cytokine patterns induced by vaccinations with either killed (i.e. formalin-inactivated, alum-precipitated) virus (KV) or live virus (LV) have been shown to influence disease expression. To determine the mRNA expression of the cytokines IL-4 and IFN-gamma in BALB/c mice challenged with RSV, a real-time quantitative reverse-transcriptase PCR assay was developed. This assay uses 5'-exonuclease fluorogenic probes and is performed on the ABI PRISM 7700 Sequence Detector System (TaqMan). The relative quantitative levels of mRNA for IL-4 and IFN-gamma were compared with those measured by an RNase protection assay (RPA) and an enzyme immunoassay (EIA), which are methods used to measure the levels of mRNA and protein, respectively. Results obtained by the TaqMan assay showed that mice primed with KV induces increased IL-4 mRNA production while LV induces increased IFN-gamma mRNA, which is in agreement with conventional methods. IL-4 and IFN-gamma relative quantities obtained from TaqMan were highly correlated to those determined by RPA (r=0.96 for IFN-gamma, P<0.01) and EIA (r=0.90 for IL-4 and r=0.75 for IFN-gamma, P<0.01). Assay reproducibility was examined by testing a same sample in triplicate at three experiments. Minimal deviation values were observed in both intra- and inter-assays. TaqMan, which is rapid, sensitive and reproducible, provides an alternative tool for the quantitative analysis of cytokine mRNA expression in the murine model of RSV immunopathogenesis.

Quantitation of expressed message for inducible nitric oxide synthase

Methodology for the analysis of expressed message has evolved rather rapidly since the early 1990s and will undoubtedly continue to evolve with new technology. cRNA standards are a useful tool, which allow for absolute rather than relative quantification of an expressed message. Selecting an appropriate sequence(s) for analysis has become even more important as techniques have evolved from Northern hybridization where possible multiple hybridization bands can be observed to real-time Rt-PCR approaches where only a signal is recorded. NOS2 presents a particular problem in this regard because of the high conservation of sequence with NOS1 and NOS3, as well as the existence of both multiple genes and splice variants, which may be of experimental importance.

B-lymphocyte deficiency increases atherosclerosis in LDL receptor-null mice

OBJECTIVE

Atherosclerosis is an inflammatory disease characterized by innate and adaptive immune responses. We investigated the role of B cells and antibodies in the development of atherosclerosis in low density lipoprotein (LDL) receptor-deficient (LDLR(-/-)) mice.

METHODS AND RESULTS

Using wild-type and B cell-deficient mice as bone marrow donors, we were able to generate LDLR(-/-) mice that possessed <1.0% of their normal B cell population. B cell-deficient LDLR(-/-) mice on a Western diet showed marked decreases in total serum antibody and anti-oxidized LDL antibody. B cell deficiency was associated with a 30% to 40% increase in the lesion area in the proximal and distal aortas. Real-time reverse transcription-polymerase chain reaction and enzyme-linked immunospot analyses showed a decrease in proatherogenic (interferon-gamma) and antiatherogenic (interleukin-10 and transforming growth factor-beta) cytokine mRNA and a decrease in interleukin-4- and interferon-gamma-producing cells. Additionally, we observed a decrease in splenocyte proliferation to oxidized LDL in the B cell-deficient LDLR(-/-) mice, suggesting that B lymphocytes may play a role in the presentation of lipid antigen.

CONCLUSIONS

Collectively, these data demonstrate that B cells and/or antibodies are protective against atherosclerosis and that this protection may be conferred by B cell-mediated immune regulation.

Use of gDNA as internal standard for gene expression in staphylococci in vitro and in vivo

An internal RNA standard proved less suitable in bacterial gene expression experiments. We therefore developed a method for simultaneous RNA and gDNA (genomic DNA) isolation from in vitro and in vivo samples containing staphylococci and combined it with quantitative PCR. The reliability of gDNA for bacterial quantification and for standardisation in gene expression experiments was evaluated. Quantitative PCR proves equivalent to quantitative culture for in vitro samples, and superior for in vivo samples. In gene expression experiments, gDNA permits a good standardisation for the initial amount of bacteria. The average interassay variability of the in vitro expression is 20.1%. The in vivo intersample variability was 73.3%. This higher variability can be attributed to the biological variation of gene expression in vivo. This method permits exact quantification of the number of bacteria and the expression of genes in staphylococci in vivo (e.g., in biofilms, evolution in time) and in vitro.