Donor-Specific Antibodies Are Produced Locally in Ectopic Lymphoid Structures in Cardiac Allografts

Cardiac allograft vasculopathy (CAV) is a transplant pathology, limiting graft survival after heart transplantation. CAV arteries are surrounded by ectopic lymphoid structures (ELS) containing B cells and plasma cells. The aim of this study was to characterize the antigenic targets of antibodies produced in ELS. Coronary arteries and surrounding epicardial tissue from 56 transplant recipients were collected during autopsy. Immunofluorescence was used to identify antibody-producing plasma cells. Immunoglobulin levels in tissue lysates were measured by enzyme-linked immunosorbent assay and analyzed for donor-specific HLA antibodies by Luminex assay. Cytokine and receptor expression levels were quantified using quantitative polymerase chain reaction. Plasma cells in ELS were polyclonal and produced IgG and/or IgM antibodies. In epicardial tissue, IgG (p < 0.05) and IgM levels were higher in transplant patients with larger ELS than smaller ELS. In 4 of 21 (19%) patients with ELS, donor-specific HLA type II antibodies were detected locally. Cytokine and receptor expression (CXCR3, interferon γ and TGF-β) was higher in large ELS in the epicardial tissue than in other vessel wall layers, suggesting active recruitment and proliferation of T and B lymphocytes. ELS exhibited active plasma cells producing locally manufactured antibodies that, in some cases, were directed against the donor HLA, potentially mediating rejection with major consequences for the graft.

Disruption of collagen homeostasis can reverse established age-related myocardial fibrosis

Heart failure, the leading cause of hospitalization of elderly patients, is correlated with myocardial fibrosis (ie, deposition of excess extracellular matrix proteins such as collagen). A key regulator of collagen homeostasis is lysyl oxidase (LOX), an enzyme responsible for cross-linking collagen fibers. Our objective was to ameliorate age-related myocardial fibrosis by disrupting collagen cross-linking through inhibition of LOX. The nonreversible LOX inhibitor β-aminopropionitrile (BAPN) was administered by osmotic minipump to 38-week-old C57BL/6J male mice for 2 weeks. Sirius Red staining of myocardial cross sections revealed a reduction in fibrosis, compared with age-matched controls (5.84 ± 0.30% versus 10.17 ± 1.34%) (P < 0.05), to a level similar to that of young mice at 8 weeks (4.9 ± 1.2%). BAPN significantly reduced COL1A1 mRNA, compared with age-matched mice (3.5 ± 0.3-fold versus 15.2 ± 4.9-fold) (P < 0.05), suggesting that LOX is involved in regulation of collagen synthesis. In accord, fibrotic factor mRNA expression was reduced after BAPN. There was also a novel increase in Ly6C expression by resident macrophages. By interrupting collagen cross-linking by LOX, the BAPN treatment reduced myocardial fibrosis. A novel observation is that BAPN treatment modulated the transforming growth factor-β pathway, collagen synthesis, and the resident macrophage population. This is especially valuable in terms of potential therapeutic targeting of collagen regulation and thereby age-related myocardial fibrosis.

Regulation and role of connective tissue growth factor in AngII-induced myocardial fibrosis

Exposure of rodents to angiotensin II (AngII) is a common model of fibrosis. We have previously shown that cellular infiltration of bone marrow-derived progenitor cells (fibrocytes) occurs before deposition of extracellular matrix and is associated with the production of connective tissue growth factor (CTGF). In the present study, we characterized the role of CTGF in promoting fibrocyte accumulation and regulation after AngII exposure. In animals exposed to AngII using osmotic minipumps (2.0 μg/kg per min), myocardial CTGF mRNA peaked at 6 hours (21-fold; P < 0.01), whereas transforming growth factor-β (TGF-β) peaked at 3 days (fivefold; P < 0.05) compared with saline control. Early CTGF expression occurred before fibrocyte migration (1 day) into the myocardium or ECM deposition (3 days). CTGF protein expression was evident by day 3 of AngII exposure and seemed to be localized to resident cells. Isolated cardiomyocytes and microvascular endothelial cells responded to AngII with increased CTGF production (2.1-fold and 2.8-fold, respectively; P < 0.05), which was abolished with the addition of anti-TGF-β neutralizing antibody. The effect of CTGF on isolated fibrocytes suggested a role in fibrocyte proliferation (twofold; P < 0.05) and collagen production (2.3-fold; P < 0.05). In summary, we provide strong evidence that AngII exposure first resulted in Smad2-dependent production of CTGF by resident cells (6 hours), well before the accumulation of fibrocytes or TGF-β mRNA up-regulation. In addition, CTGF contributes to fibrocyte proliferation in the myocardium and enhances fibrocyte differentiation into a myofibroblast phenotype responsible for ECM deposition.

Treatment with activated protein C (aPC) is protective during the development of myocardial fibrosis: an angiotensin II infusion model in mice

Aims

Myocardial fibrosis contributes to the development of heart failure. Activated Protein C (aPC) is a circulating anticoagulant with anti-inflammatory and cytoprotective properties. Using a model of myocardial fibrosis second to Angiotensin II (AngII) infusion, we investigated the novel therapeutic function aPC in the development of fibrosis.

Methods and Results

C57Bl/6 and Tie2-EPCR mice were infused with AngII (2.0 µg/kg/min), AngII and aPC (0.4 µg/kg/min) or saline for 3d. Hearts were harvested and processed for analysis or used for cellular isolation. Basic histology and collagen deposition were assessed using histologic stains. Transcript levels of molecular mediators were analyzed by quantitative RT-PCR. Mice infused with AngII exhibited multifocal areas of myocardial cellular infiltration associated with significant collagen deposition compared to saline control animals (p<0.01). AngII-aPC infusion inhibited this cellular infiltration and the corresponding collagen deposition. AngII-aPC infusion also inhibited significant expression of the pro-fibrotic cytokines TGF-β1, CTGF and PDGF found in AngII only infused animals (p<0.05). aPC signals through its receptor, EPCR. Using Tie2-EPCR animals, where endothelial cells over-express EPCR and exhibit enhanced aPC-EPCR signaling, no significant reduction in cellular infiltration or fibrosis was evident with AngII infusion suggesting aPC-mediate protection is endothelial cell independent. Isolated infiltrating cells expressed significant EPCR transcripts suggesting a direct effect on infiltrating cells.

Conclusions

This data indicates that aPC treatment abrogates the fibrogenic response to AngII. aPC does not appear to confer protection by stimulating the endothelium but by acting directly on the infiltrating cells, potentially inhibiting migration or activation.

Cyclosporine immunosuppression does not prevent the production of donor-specific antibody capable of mediating allograft vasculopathy

BACKGROUND

Late cardiac graft rejection, primarily mediated by allograft vasculopathy (AV), remains a major limitation to cardiac transplantation, even in the face of significant calcineurin inhibitor (CNI) immunosuppression. The role played by alloantibody in AV is unclear. Evidence that CNI immunosuppression suppresses CD4(+) T-cell function would suggest that antibody production and effector function would be severely limited in CNI-treated patients. In this study we examine the capacity of CNI-treated animals to develop effective alloantibody that can mediate AV.

METHODS

Wild-type (WT) B6 mice were alloimmunized using donor splenocytes or a fully major histocompatibility complex-mismatched allogeneic abdominal aortic graft in the presence of CNI immunosuppression (30 or 50 mg/kg/day cyclosporine A). Anti-serum was harvested and tested using complement-dependent in vitro cytotoxicity assays. Anti-serum was passively transferred to immunodeficient RAG1(-/-) recipients of allogeneic grafts. C4d deposition was quantified in the allografts from WT recipients.

RESULTS

CNI immunosuppression did not prevent the development of alloantibody in response to either immunization method (p < 0.05). Passive transfer of anti-serum generated AV lesions in immunodeficient graft recipients and mediated complement-dependent destruction of donor cells (p < 0.05). C4d deposition was localized to the media of grafts of CNI treated animals.

CONCLUSIONS

CNI therapy does not prevent the production of alloantibody with the capacity to mediate AV. C4d deposition in the media suggests a role for medial smooth muscle cell loss in antibody-mediated AV lesion development in our model.

Fibroblast progenitor cells are recruited into the myocardium prior to the development of myocardial fibrosis

Using an established model of myocardial hypertrophy and fibrosis after angiotensin II (AngII) infusion, our aim was to characterize the early cellular element involved in the development of myocardial fibrosis in detail. Male Lewis rats were infused with saline or AngII (0.7 mg/kg per day) for up to seven days. Collagen deposition and cellular infiltration were identified by histology stains. Infiltrating cells were grown in vitro and examined by flow cytometry and immunostaining. Chemokine expression was measured using qRT-PCR. AngII infusion resulted in multifocal myocardial cellular infiltration (peak at three days) that preceded collagen deposition. Monocyte chemotactic protein (MCP)-1 transcripts peaked after one day of AngII exposure. Using a triple-labelling technique, the infiltrating cells were found to express markers of leucocyte (ED1(+)), mesenchymal [α-smooth muscle actin (SMA)(+)] and haematopeotic progenitor cells (CD133(+)) suggesting a fibroblast progenitor phenotype. In vitro, ED1(+)/SMA(+)/CD133(+) cells were isolated and grown from AngII-exposed animals. Comparatively few cells were cultured from untreated control hearts, and they were found to be ED1(-)/SMA(+)/CD133(-). We provide evidence that myocardial ECM deposition is preceded by infiltration into the myocardium by cells that express a combination of haematopoietic (ED1, CD133) and mesenchymal (SMA) cell markers, which is a characteristic of the phenotype of fibroblast precursor cells, termed fibrocytes. This suggests that fibrocytes rather than (as is often presumed) leucocytes may have effector functions in the initiation of myocardial fibrosis.

Early innate immune events induced by prolonged cold ischemia exacerbate allograft vasculopathy

BACKGROUND

Ischemia/reperfusion induced innate immune injury is inescapable in solid organ transplantation. Prolonged cold ischemia exacerbates the primary manifestation of late graft rejection, allograft vasculopathy (AV). The relationship between prolonged cold ischemia and late graft events is unclear and the subject of this study.

METHODS

Aortic interposition transplants were performed between fully disparate mice treated with CyclosporineA. Allografts were exposed to 20 min or 60 min of cold ischemia and harvested between 1 d-6 wk. Lesion size, smooth muscle cells (SMC), neutrophils (NØ), and CD8+ T cells were quantified.

RESULTS

Early SMC loss was identical in both groups. When compared to 20 min cold ischemia, grafts exposed to 60 min exhibited greater early NØ influx, greater SMC proliferation but fewer medial SMC at 1 wk and 2 wk. Subsequently, earlier and greater CD8+ T cell infiltration were seen in the 60 min group with larger lesions at every time point.

CONCLUSIONS

These data suggest that the larger neointimal lesions in grafts exposed to 60 min cold ischemia result from enhanced early innate immune events resulting in impaired SMC recovery and subsequent increased adaptive immune response.

Antimycobacterial screening of traditional medicinal plants using the microplate resazurin assay

Multidrug-resistant Mycobacterium tuberculosis strains have rapidly become a global health concern. North American First Nations communities have used traditional medicines for generations to treat many pulmonary infections. In this study, we evaluated the antimycobacterial activity of 5 medicinal plants traditionally used as general therapeutics for pulmonary illnesses and specifically as treatments for tuberculosis. Aqueous extracts of Aralia nudicaulis, Symplocarpus foetidus, Heracleum maximum, Juniperus communis, and Acorus calamus were screened for antimycobacterial activity against Bacillus Calmette-Guérin, Mycobacterium avium, and M. tuberculosis H37Ra using the colorimetric microplate resazurin assay. Extracts of Acorus calamus and H. maximum root demonstrated significant antimycobacterial activity comparable to that of the rifampin control (2 microg/mL). Evaluation of the cytotoxicity of these 2 extracts using the MTT assay also showed that the extracts were less toxic to 3 human cell lines than was the DMSO positive control. This study demonstrates that aqueous extracts of the roots of H. maximum and Acorus calamus possess strong in vitro antimycobacterial activity, validates traditional knowledge, and provides potential for the development of urgently needed novel antituberculous therapeutics.

Neutrophil mediated smooth muscle cell loss precedes allograft vasculopathy

BACKGROUND

Cardiac allograft vasculopathy (AV) is a pathological process of vascular remodeling leading to late graft loss following cardiac transplantation. While there is consensus that AV is alloimmune mediated, and evidence that the most important alloimmune target is medial smooth muscle cells (SMC), the role of the innate immune response in the initiation of this disease is still being elucidated. As ischemia reperfusion (IR) injury plays a pivotal role in the initiation of AV, we hypothesize that IR enhances the early innate response to cardiac allografts.

METHODS

Aortic transplants were performed between fully disparate mouse strains (C3H/HeJ and C57BL/6), in the presence of therapeutic levels of Cyclosporine A, as a model for cardiac AV. Neutrophils were depleted from some recipients using anti-PMN serum. Grafts were harvested at 1,2,3,5d and 1,2wk post-transplant. Ultrastructural integrity was examined by transmission electron microscopy. SMC and neutrophils were quantified from histological sections in a blinded manner.

RESULTS

Grafts exposed to cold ischemia, but not transplanted, showed no medial SMC loss and normal ultrastructural integrity. In comparison, allografts harvested 1d post-transplant exhibited > 90% loss of SMC (p < 0.0001). SMC partially recovered by 5d but a second loss of SMC was observed at 1wk. SMC loss at 1d and 1wk post-transplant correlated with neutrophil influx. SMC loss was significantly reduced in neutrophil depleted recipients (p < 0.01).

CONCLUSIONS

These novel data show that there is extensive damage to medial SMC at 1d post-transplant. By depleting neutrophils from recipients it was demonstrated that a portion of the SMC loss was mediated by neutrophils. These results provide evidence that IR activation of early innate events contributes to the etiology of AV.

Activation of innate immunity to reduce lung metastases in breast cancer

Breast cancer continues to be one of the leading causes of cancer death in women. Mortality is primarily due to the development of metastases. Although therapies exist, they lack efficacy in preventing metastatic growth. As a result, novel agents are being investigated. In particular, treatments that target the immune system are being examined as potential anti-neoplastic agents. Cordyceps sinensis (Cs) is a fungus that has been used for over 2,000 years in China as a treatment for a variety of conditions including neoplasms. The available evidence suggests that efficacy of Cs as an anti-neoplastic therapeutic agent is related to a role as an activator of innate immune responses. The objectives of this study were: to investigate the ability of Cs to activate macrophages to produce factors that will induce protective responses against tumour growth; to study the ability of Cs to reduce primary tumour growth in vivo; and to examine the ability of Cs to reduce lung metastasis growth in vivo. We found that oral Cs does not reduce primary tumour growth but can reduce lung metastasis occurrence in a surgical excision model of metastatic mammary carcinoma. The evidence we have shown to date suggests that the reduction in metastases growth may be due to the effects of macrophage-derived factors on tumour cell cycle.

Contribution of pre-existing vascular disease to allograft vasculopathy in a murine model

Allograft vasculopathy (AV) has emerged as a major obstacle for long-term graft survival after cardiac transplantation. The shortage of donor hearts has meant fewer restrictions have been placed on acceptable hearts over the past few years resulting in an increase in the number of older hearts in the donor pool. This increase has subsequently led to the increase of donor hearts containing pre-existing disease. The importance of this pre-existing donor vascular disease in AV outcomes remains controversial. In this study we address this by taking advantage of the fact that B6 Apolipoprotein-E knockout mice develop atherosclerotic lesions in their aortic tracts that closely model human naturally occurring vascular disease. By using these mice as donors, we transplant known levels of pre-existing disease into fully disparate (C3H) recipients. Cyclosporin A is used to prevent acute rejection and allow for allograft vasculopathy. We found that pre-existing lesions are retained in this model after transplantation and that they contribute to increase in lesion size and to increased lumenal narrowing. The de novo AV lesions overlay the pre-existing lesions and this leads to areas of eccentric lesion formation in the vessels with likely accompanying exacerbation of flow perturbation.

Echinacea-induced macrophage activation

Public interest in Echinacea is growing rapidly. Unfortunately, there is little scientific evidence to support claims of efficacy of this widely used botanical, and little information about potential mechanism of action. This study examines the ability of Echinacea to upregulate macrophage function and begins to elucidate the mechanism of Echinacea-induced macrophage activation. Murine peritoneal macrophages were cultured with E. purpurea extracts enriched for plant polysaccharide (EP). ELISA was used to measure cytokine production. MAPKs were blocked using specific inhibitors, and Western blotting used to identify phosphorylated proteins involved in signal transduction. To examine in vivo efficacy, EP was administered orally and Listeria monocytogenes given i.v. Mice were sacrificed three days post-infection to determine bacterial load in the spleen. We demonstrate that an endotoxin-free EP extract activates the innate immune response, stimulating production of IL-6, TNF, IL-12, and NO from macrophages in vitro. Along with evidence of enhanced macrophage function, we found that oral EP reduces bacterial burden during infection by Listeria monocytogenes, demonstrating its efficacy in vivo. EP initiates a signaling cascade within macrophages through both TLR4-dependent and -independent mechanisms, involving ERK, p38 and JNK, and ultimately the activation of NF-kappaB.

Immunostimulant properties of Heracleum maximum Bartr

The root of Heracleum maximum Bartr. (Umbelliferae), known to possess direct antifungal and anti-mycobacterial properties, has been reported anecdotally to possess antiviral properties. It was therefore hypothesized that the plant may have immunostimulant properties. This hypothesis was tested using a macrophage activation assay to evaluate the ability of aqueous extracts of the root of Heracleum maximum to stimulate IL-6 production. All Heracleum maximum extracts were found to stimulate IL-6 and produced a steep dose-response curve. With the assay performed twice in the absence of the macrophage primer, IFN-gamma, the mean IL-6 production in the setting of the strongest extract was 3648pg/ml (95% CI 3361-3935) and 5430pg/ml (95% CI 4976-5885) as compared to 2722pg/ml (95% CI 2620-2824) and 6772pg/ml (95% CI 6282-7262) produced by the LPS positive control, respectively. In the presence of IFN-gamma, the strongest extract produced a mean concentration of IL-6 of 21804pg/ml (95% CI 19755-23854) surpassing the 14893pg/ml (13159-16628) produced by the LPS+IFN-gamma positive control. These positive results confirm the hypothesis of immunostimulation and thus support the anecdotal reports of antiviral activity.

Aortic allograft vasculopathy is mediated by CD8(+) T cells in Cyclosporin A immunosuppressed mice

We investigated the role of CD4(+) T cells and CD8(+) T cells in mediating allograft vasculopathy in Cyclosporin A (CyA) immunosuppressed mice. We first established that a dose of 50 mg/kg/d CyA was required to prevent acute rejection in C57BL/6 mice. CyA given at 50 mg/kg/d did not prevent allograft vasculopathy in either cardiac or aortic transplants in these mice. Using CD4(-/-) and CD8(-/-) mice, we established that CyA immunosuppression at this dose was only effective at preventing allograft vasculopathy in mice lacking CD8(+) T cells. This implicates CD8(+) T cells in the development of AV in situations of clinical cardiac transplantation where CyA is still the mainstay of immunosuppressive therapy. We confirmed the important role for CD8(+) T cells in AV in the face of CyA immunosuppression by allopriming mice in the presence of CyA and transferring alloprimed T cells into RAG1(-/-) immunodeficient mice. The RAG1(-/-) mice were also treated with CyA. In this situation (CyA present during the allopriming and in the recipient), only primed CD8(+) T cells could mediate AV, primed CD4(+) T cells could not. Alloprimed CD8(+) T cells raised in the presence of CyA exhibited markedly reduced direct recognition responses (as measured by MLR) and effector responses (as measured by cytotoxic activity). In contrast indirect activation was retained. We interpret these data to suggest that in the face of CyA immunosuppression CD4(+) T cell effector function is ablated while CD8(+) T cell function remains partially intact. The in vitro data suggest that the indirect pathway remains intact in this population of CyA resistant CD8(+) T cells.

Impairment of recipient cytolytic activity attenuates allograft vasculopathy

We investigated the role of CD4+ and CD8+ T subsets as well as T cell cytolytic effector mechanisms in the aortic allograft model of allograft vasculopathy using CD4 and CD8 gene knockout mice (CD4(-/-), CD8(-/-)) and mice deficient in cytolytic effector pathways. Medial apoptosis at 2 weeks was reduced in CD8(-/-) mice and in mice where cytotoxic T cell activity was compromised. At 8 weeks, substantial medial damage was observed in wild-type (WT) and CD4(-/-) recipients but medial preservation was evident in CD8(-/-) mice and in mice with impaired cytotoxic T cell activity. The intima/media ratio, a comprehensive measure of allograft vasculopathy, was similar in WT and CD4(-/-) recipients but was significantly reduced in CD8(-/-) mice and mice with impaired cytotoxic T cell activity. These data indicate that CD8+ T cells contribute to the vascular remodeling that is characteristic of allograft vasculopathy. They also show that CD8+ T cells participate in allograft vasculopathy in the absence of CD4+ T cell help. We further demonstrated that WT mice exhibited robust allograft vasculopathy in the presence of cyclosporin A immunosuppression but that allograft vasculopathy was ablated in cyclosporin-treated CD8(-/-) mice. This supports the hypothesis that non-CD8+ T cell effector mechanisms are sensitive to calcineurin inhibitor therapy but that CD8+ T cell-mediated allograft vasculopathy is refractory to such treatment. Taken together, our data suggest that CD8+ T cells contribute to the induction of vascular remodeling in allograft vasculopathy and provide evidence that novel therapies which target CD8+ T cell effector function might be effective in mitigating AV in the clinical setting.

CD8 T cells mediate aortic allograft vasculopathy by direct killing and an interferon-?-dependent indirect pathway

OBJECTIVE

Allograft vasculopathy (AV) has emerged as the major obstacle to long-term survival in clinical heart transplantation. Immune events are implicated in the development of AV, but the cellular and molecular mechanisms involved remain unclear. We sought to determine whether and by what mechanism CD8(+) T lymphocytes are able to generate AV in a murine aortic allograft model.

METHODS

Allo-primed CD8(+) T lymphocytes were transferred into immunodeficient (RAG-1(-/-)) mouse recipients of aortic allografts. We also transferred primed CD8(+) T cells with targeted deletions of effector molecules (perforin, Fas-ligand) to determine the role of direct cytolysis (CTL) in CD8(+) T-cell-mediated AV. We determined the role of non-CTL effector mechanisms through the transfer of either wildtype or interferon-gamma (IFN-gamma)-deficient CD8(+) T cells into RAG-1(-/-) recipients of MHC class I-deficient allografts.

RESULTS

Adoptive transfer of primed wildtype CD8(+) T lymphocytes into immunodeficient recipients of aortic allografts resulted in the development of robust AV lesions. Transfer of CD8(+) T lymphocytes with targeted deletions in CTL effector molecules resulted in reduction of AV lesion size but not abrogation. Transfer of wildtype CD8(+) T cells into recipients of MHC class I-deficient grafts resulted in a reduction in AV lesion size, while transfer of interferon-gamma-deficient CD8(+) T cells into MHC class I-deficient grafts abrogated AV.

CONCLUSIONS

These data indicate that CD8(+) T cells mediate AV through direct cytolysis and a distinct interferon-gamma-dependent non-CTL effector pathway. Given the resistance of this cell type to conventional immunosuppression, these results may have important therapeutic implications.

Reduced tumorigenicity of B16-F10 mouse melanoma cells transfected with mycobacterial antigen 85A

Immunotherapy based on the administration of the mycobacterium bacillus Calmette-Guerin has been successfully used in the treatment of in situ transitional cell bladder cancer, and may be applicable to the treatment of cutaneous malignant melanoma. Antigen 85A (Ag85A) and heat shock protein 65 kDa (hsp65) are major secreted proteins of Mycobacterium species and potent stimulators of cell-mediated immunity. This study evaluated the ability of Ag85A and hsp65 gene transfection to limit tumor growth by B16-F10 mouse melanoma cells. Immunoblotting confirmed protein expression and secretion by B16-F10 cells that were transiently transfected with plasmid DNA containing the Ag85A or hsp65 gene. Groups of syngeneic C57BL/6 mice were injected subcutaneously with 1x10(5) untransfected B16-F10 cells or B16-F10 cells transiently transfected with either empty vector or vector containing the Ag85A or hsp65 gene. Ag85A-expressing B16-F10 cells exhibited a dramatic 76% reduction (p<0.05, Mann-Whitney U test) in tumor weight in comparison to empty vector controls at 14 days post-inoculation. In contrast, hsp65-transfected B16-F10 cells did not show any change in tumorigenicity. Decreased tumorigenicity by Ag85A-transfected B16-F10 cells was not due to a reduced ability of Ag85A-transfected B16-F10 cells to proliferate since both mock- and Ag85A-transfected B16-F10 cells showed increased in vitro proliferation in comparison to untransfected cells. Hematoxylin and eosin staining revealed that Ag85A-transfected B16-F10 tumors contained an inflammatory leukocyte infiltrate that was not present in hsp65-transfected tumors. Reduced tumor progression by Ag85A-transfected B16-F10 melanoma cells suggests that immunotherapy based on the transient induction of Ag85A expression may be an effective approach for the treatment of cutaneous malignant melanoma.

Reduction in postoperative adhesion formation and re-formation after an abdominal operation with the use of N, O - carboxymethyl chitosan

BACKGROUND

Postoperative adhesions have proven to be intractable complications after abdominal operations. This study assessed the efficacy of N, O - carboxymethyl chitosan (NOCC) to limit adhesion formation and re-formation in a rabbit abdominal surgery model.

METHODS

In study 1 (adhesion formation), injuries to the large bowel, cecum, and abdominal sidewall were generated in rabbits. The rabbits (10/group) were randomly assigned to 1 of 5 treatment groups: Group A received no NOCC treatment; in group B, NOCC gel was applied directly to the injured site and NOCC solution was applied throughout the abdominal cavity; in group C, NOCC gel was applied near the injured site and NOCC solution was applied as above; in group D, NOCC gel was applied distant to the injury and NOCC solution was applied as above; in group E, a mixture of NOCC gel and solution was applied at the injured site. Adhesions were evaluated 14 days later. In study 2 (adhesion re-formation), adhesions were generated as above but were then lysed by careful dissection. After adhesiolysis, the rabbits (9/group) were treated with NOCC gel and solution at the site of adhesiolysis or left untreated. Adhesion re-formation was assessed 14 days later. In study 3 (mechanism of action), sterile tissue culture plates were coated with NOCC and adhesion of cultured, radiolabeled murine fibroblasts to the plates was assessed.

RESULTS

In study 1, animals treated with NOCC gel and solution showed reduced adhesion formation (P<.01). NOCC gel was equally efficacious if applied on the site of injury or near the site of injury but less efficacious if applied at a site distant to the injury. In study 2, animals treated with NOCC gel and solution showed less adhesion re-formation compared with the untreated control animals (P<.01). In study 3, murine fibroblasts did not adhere to NOCC-coated tissue culture plates.

CONCLUSIONS

NOCC gel and solution can reduce adhesion formation and re-formation in this rabbit model. The inability of fibroblasts to adhere to NOCC solution-coated surfaces suggests that NOCC may act as a biophysical barrier.

Efficacy of a standardized echinacea preparation (EchinilinTM) for the treatment of the common cold: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Recently, echinacea has regained popularity as one of the treatments chosen most commonly by consumers with the expectation that it will reduce the severity and duration of the common cold. However, the results from a limited number of clinical trials for this application have thus far been inconclusive. This incongruity may be the result of investigators utilizing poorly standardized echinacea products, likely devoid of sufficient quantities of active constituents necessary to exert a definitive clinical effect. Therefore, a formulation containing alkamides, cichoric acid, and polysaccharides at concentrations of 0.25, 2.5, and 25 mg/mL, respectively, was prepared from freshly harvested Echinacea purpurea plants (commercially available as Echinilin, Natural Factors Nutritional Products, Inc., Vancouver, BC, Canada). The objective of this study was to test the efficacy of this highly standardized formulation in reducing the severity and duration of symptoms of a naturally acquired common cold.

METHODS

In a randomized, double-blind, placebo-controlled trial, 282 subjects aged 18-65 years with a history of two or more colds in the previous year, but otherwise in good health, were recruited. The subjects were randomized to receive either echinacea or placebo. They were instructed to start the echinacea or placebo at the onset of the first symptom related to a cold, consuming 10 doses the first day and four doses per day on subsequent days for 7 days. Severity of symptoms (10-point scale: 0, minimum; 9, maximum) and dosing were recorded daily. A nurse examined the subjects on the mornings of days 3 and 8 of their cold.

RESULTS

A total of 128 subjects contracted a common cold (59 echinacea, 69 placebo). The total daily symptom scores were found to be 23.1% lower in the echinacea group than in placebo in those who followed all elements of the study protocol (P<0.01). Throughout the treatment period, the response rate to treatments was greater in the echinacea group. A few adverse event profiles were observed in both groups.

CONCLUSIONS

Early intervention with a standardized formulation of echinacea resulted in reduced symptom severity in subjects with naturally acquired upper respiratory tract infection. Further studies with larger patient populations appear to be warranted.

Recipient cells form the proliferative lesion in the rat heterotopic tracheal allograft model of obliterative airway disease

To determine the nature of the proliferative lesion in obliterative airway disease, heterotopic tracheal allograft transplantation was performed between fully disparate Brown Norway and Lewis rat strains. Four weeks after transplantation, the resulting lumenal occlusive lesion was stripped from the underlying tissue. The lesion was probed using immunohistochemical analysis with monoclonal antibodies and for DNA using strain-specific primers for Brown Norway or Lewis major histocompatibility complex Class I alleles. The lesions were alpha-actin positive, and polymerase chain reaction probing revealed only recipient DNA in the lesion tissue, regardless of the direction of transplantation, with no amplification of donor DNA. From this, we conclude that the proliferative lesion in the rat heterotopic tracheal model is of recipient origin a finding with important implications for the pathobiology of obliterative airway disease.

Murine hypodense eosinophils induce tumour cell apoptosis by a granzyme B-dependent mechanism

PURPOSE

Eosinophils have been shown to potentiate anti-tumour cytotoxicity in both clinical and animal studies. The mechanism by which eosinophils induce tumour cell damage, however, has largely been speculative. The purpose of this study was to identify the mechanisms involved in eosinophil-induced tumour cell cytotoxicity.

METHODS

To investigate eosinophil cytotoxicity, eosinophils were isolated from the peritoneal cavity of Mesocestoides corti-infected BALB/c mice, and were separated into normodense (ND) and hypodense (HD) populations using discontinuous Percoll density gradient centrifugation. The tumoricidal activity of ND and HD eosinophils was assessed using the [51Cr]-release cytotoxicity assay (a measure of cytolytic activity) and the JAM assay (a measure of apoptotic activity). Investigation of apoptosis-inducing molecules in HD eosinophils was undertaken by RT-PCR. The calcium chelator EGTA, serine protease inhibitor aprotinin and a competitive substrate for granzyme B were used to assess the role of perforin and granzyme B in HD eosinophil killing.

RESULTS

Cytotoxic activity induced by HD eosinophils was significantly greater than that of ND eosinophils, and apoptosis was the principal killing mechanism. RT-PCR analysis revealed that HD eosinophils express mRNA for perforin, granzyme B and Fas ligand. Furthermore, HD eosinophil killing was markedly inhibited by EGTA, intracellular aprotinin and the granzyme B competitive substrate.

CONCLUSIONS

These data are consistent with a hypothesis that murine HD eosinophils elicit tumoricidal activity via a granzyme B-dependent mechanism.

Nematode Infection Enhances Survival of Activated T Cells by Modulating Accessory Cell Function

The type of immune response generated following exposure to Ag depends on a variety of factors, including the nature of the Ag, the type of adjuvant used, the site of antigenic entry, and the immune status of the host. We have previously shown that infection of rodents with Nippostrongylus brasiliensis (Nb) shifts the development of type 1 allo-specific responses toward type 2 immunity, suggesting nematode modulation of T cell activation. In this report we explore the immunomodulatory effects of Nb on T cell activation. We found that spleen cells from Nb-infected mice exhibited dramatically increased proliferation in response to Con A and anti-CD3. This hyperproliferation could be transferred in vitro to naive splenocytes by coculture with mitomycin C-treated cells from Nb-infected animals. The transfer was mediated by non-T accessory cells and supernatants derived from Con A-activated non-T cells, suggesting the involvement of a soluble factor secreted by accessory cells. The accessory cells secreted high levels of IL-6, and anti-IL-6 treatment abrogated the supernatant-induced hyperproliferation, thus confirming that IL-6 was mediating the effect. Further, spleen cells from Nb-infected mice were more resistant to activation-induced cell death (AICD) following mitogenic stimulation. Reduced AICD was also transferable and IL-6 dependent. Thus, the hyperproliferation was in part due to enhanced activated T cell survival. These phenomena mediated by accessory cells may contribute to the powerful polyclonal activation of type 2 immunity caused by nematode infection.