Susan L. Hill

Flexible transgastric peritoneoscopy: a novel approach to diagnostic and therapeutic interventions in the peritoneal cavity

BACKGROUND A novel endoscopic peroral transgastric approach to the peritoneal cavity was tested in a porcine model in acute and long-term survival experiments. METHODS Transgastric peritoneoscopy was evaluated in 50-kg pigs. After upper endoscopy, the peritoneal cavity was accessed by needle-knife puncture of the gastric wall, followed by extension of the incision either with a pull-type sphincterotome or by balloon dilation. The peritoneal cavity was examined, and a liver biopsy specimen was obtained. The gastric wall incision was closed with clips. OBSERVATIONS Twelve acute and 5 survival experiments were performed. Both techniques of gastric wall incision were without complication. The acute experiments demonstrated the technical feasibility of the approach. In the survival experiments, all pigs recovered and gained weight. CONCLUSIONS The peroral transgastric approach to peritoneal cavity technically is feasible and has the potential to be an alternative to laparoscopy and laparotomy.

Nitric oxide inhibits viral replication in murine myocarditis.

Nitric oxide (NO) is a radical molecule that not only serves as a vasodilator and neurotransmitter but also acts as a cytotoxic effector molecule of the immune system. The inducible enzyme making NO, inducible NO synthase (iNOS), is transcriptionally activated by IFN-gamma and TNF-alpha, cytokines which are produced during viral infection. We show that iNOS is induced in mice infected with the Coxsackie B3 virus. Macrophages expressing iNOS are identified in the hearts and spleens of infected animals with an antibody raised against iNOS. Infected mice have increased titers of virus and a higher mortality when fed NOS inhibitors. Thus, viral infection induces iNOS in vivo, and NO inhibits viral replication. NO is a novel, nonspecific immune defense against viruses in vivo.

Experimental Autoimmune Myocarditis in A/J mice Is an Interleukin-4-Dependent Disease with a Th2 Phenotype

Myocarditis in humans is often associated with an autoimmune process in which cardiac myosin (CM) is a major autoantigen. Experimental autoimmune myocarditis (EAM) is induced in mice by immunization with CM. We found that EAM in A/J mice exhibits a Th2-like phenotype demonstrated by the histological picture of the heart lesions (eosinophils and giant cells) and by the humoral response (association of IgG1 response with disease and up-regulation of total IgE). Blocking interleukin (IL)-4 with anti-IL-4 monoclonal antibody (mAb) reduced the severity of EAM. This reduction in severity was associated with a shift from a Th2-like to a Th1-like phenotype represented by a reduction in CM-specific IgG1; an increase in CM-specific IgG2a; an abrogation of total IgE response; a decrease in IL-4, IL-5, and IL-13; as well as a dramatic increase in interferon (IFN)-gamma production in vitro. Based on the latter finding, we hypothesized that IFN-gamma limits disease. Indeed, IFN-gamma blockade with a mAb exacerbated disease. The ameliorating effect of IL-4 blockade was abrogated by co-administration of anti-IFN-gamma mAb. Thus, EAM represents a model of an organ-specific autoimmune disease associated with a Th2 phenotype, in which IL-4 promotes the disease and IFN-gamma limits it. Suppression of IFN-gamma represents at least one of the mechanisms by which IL-4 promotes EAM.

Characterization of Murine Autoimmune Myocarditis Induced by Self and Foreign Cardiac Myosin

Previously we showed that autoimmune myocarditis could be induced in mice by immunization with purified murine cardiac myosin (MCM). In this study, we found that identical disease could also be induced in genetically susceptible mice by immunization with porcine cardiac myosin (PCM). The cardiac lesions induced by both antigens were characterized by extensive infiltration of the myocardium accompanied by myocyte necrosis. A novel finding was the presence of multinucleated giant cells and eosinophils in the cardiac infiltrates, in addition to a mixture of mononuclear cells and polymorphonuclear cells described previously. Immunohistochemical staining demonstrated that the mononuclear cells consisted predominantly of macrophages, CD4+ T cells and, to a lesser extent, CD8+ T cells and B cells. In addition, increased cardiac expression of adhesion molecules E-selectin, vascular cell adhesion molecule-1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1) were demonstrated in mice that developed myocarditis as compared with those that did not develop disease upon immunization with either PCM or MCM. The levels of TNFalpha detected in spleen cell culture supernatant were found to be higher in mice that developed myocarditis than in those that did not develop the disease. Mice immunized with PCM generated T cells and B cells reactive not only with PCM but also with MCM, and vice versa. In addition, the serum levels of IgG1 anti-MCM antibodies produced in mice immunized with PCM as well as MCM were found to correlate positively with the development of myocarditis. Such a detailed characterization of the murine model of autoimmune myocarditis induced by PCM or MCM allowed us to compare the disease process induced by homologous self and foreign antigens.

Effect of Pre-Loading Oral Glucosamine HCl/Chondroitin Sulfate/Manganese Ascorbate Combination on Experimental Arthritis in Rats

The therapeutic effect of a nutritional supplement consisting of a combination of glucosamine hydrochloride (FCHG49), purified sodium chondroitin sulfate (TRH122), and manganese ascorbate (GCM)3 was investigated in the rat model of collagen-induced autoimmune arthritis (CIA). The GCM compound was mixed with a palatable nutritional paste (Nutri-cal® [NC]). Oral administration of the NC/GCM compound was initiated in 26 rats 10 days before immunization and continued until the day of sacrifice. One group of 12 control rats was given no oral agents; a second group of 12 control rats received NC only. Evaluations included arthritis index (AI) scoring by three independent evaluators, histologic index (HI) scoring of lesions, T-cell proliferation, and serological studies for antibody classes and subclasses. Both the AI and HI criteria showed a statistically significant reduction in the prevalence of CIA in rats pretreated with the NC/GCM (54%) compared to the combined control groups (96%, χ2 analysis P < 0.001). Rats fed the NC/GCM also exhibited a significant decrease in the severity of autoimmune arthritis in both the AI and HI compared to control Group 2 (immunized-NC) (χ2 analysis P < 0.05). Histological studies verified the decreased incidence of arthritis in the NC/GCM group compared to control Group 2. GCM treatment failed to alter T-cell proliferation and antibody production to bovine type-II collagen, indicating that its effects are not due to alteration of the antigen-specific immune response.

Nasal administration of cardiac myosin suppresses autoimmune myocarditis in mice

OBJECTIVES This study was designed to examine whether myocarditis induced in a mouse model can be effectively suppressed by nasal administration of cardiac myosin (CM). BACKGROUND Myocarditis in humans often follows viral infection and is accompanied by evidence of an autoimmune response to CM. Treatment has been hampered by the fact that measures undertaken to reduce the autoimmune response often enhance the viral infection. Delivery of antigen via nasal route has been shown to induce antigen-specific tolerance and suppress certain autoimmune diseases in animal models. METHODS Myocarditis was induced in A/J mice by two subcutaneous injections of CM emulsified in complete Freunds adjuvant. Nasal instillation of CM (200 microg/mouse) or vehicle buffer was carried out three days before the first subcutaneous injection (day -3). The effect of nasal instillation of CM on cardiac histopathology, cytokine production by splenocytes, and antibody response was examined three weeks after the first subcutaneous injection (day 21). RESULTS Nasal administration of CM effectively reduced the severity of myocarditis. Consistent with the histological findings, the levels of interleukin-2 (IL-2), tumor necrosis factor-alpha, and IL-1beta produced by splenocytes in response to CM were significantly decreased. In addition, the serum levels of IgE and IgG1 anti-myosin antibodies were suppressed. However, the levels of transforming growth factor-beta (TGF-beta) and CM-specific IgA antibodies were not affected. CONCLUSIONS Taken together, our results do not support active suppression through upregulation of TGF-beta, IL-4, and IL-10 as a mechanism of tolerance, but favor anergy or deletion of both Th1 and Th2 autoreactive T cells.

The transition from viral to autoimmune myocarditis

Myocarditis offers a unique opportunity to study the factors contributing to its transition from a viral infection to an autoimmune disease. In this article, we review recent studies on the role of nitric oxide (NO), gamma interferon (IFN-γ) and interleukin 12 (IL-12) in the progression from early (viral) to late (autoimmune) phases of myocarditis induced by Coxsackievirus B3 (CB3) in highly susceptible (A.CA) and moderately susceptible (B10.M) mice. NO plays a paradoxical role, being protective in early stages but detrimental later in the course of disease. Treatment with antibody to IFN-γ reduced early disease, but had little effect on the severity of cardiac lesions at later times. Treatment with recombinant (r) IL-12 significantly reduced the autoimmune cardiac lesions in moderately susceptible B10.M mice, but had no measurable effect in highly susceptible A.CA animals. These studies provide evidence that the profile of inflammatory mediators produced early in the course of viral infection determines the later development of autoimmune disease.

Therapeutic efficacy of halofuginone and spiramycin treatment against Cryptosporidium serpentis (Apicomplexa: Cryptosporidiidae) infections in captive snakes

Abstract The therapeutic effect of halofuginone hydrobromide (Steronol) and spiramycin solubilized (Spirasol) applied to clinical Cryptosporidium serpentis infections in captive snakes was investigated. Pathological changes induced by C. serpentis were typical for snake cryptosporidiosis. Spiramycin induced no significant change in the pattern of shedding of fecal Cryptosporidium oocysts; biopsies and necropsies revealed cryptosporidiosis in gastric mucosa of all spiramycin-treated animals. In all, 8 of 21 (38%) halofuginone-treated snakes stopped shedding C. serpentis oocysts; examination of gastric tissue of 6 of these 8 animals revealed cryptosporidiosis in 2 snakes. Hepatotoxic and nephrotoxic pathological changes induced by halofuginone included focal or multifocal, severe, acute liver necrosis; severe liver hemosiderosis; and bilateral, severe, acute diffuse cortical and tubular necrosis and iron deposition. Postprandial regurgitation associated with midbody swelling, observed in 4 halofuginone-treated and 2 spiramycin-treated snakes at 15 and 21 weeks after drug withdrawal, did not coincide with oocyst-positive feces. Neither halofuginone nor spiramycin treatment produced a satisfactory therapeutic outcome when applied against clinical C. serpentis infections in snakes.

Chapter 11 – Experimental Myocarditis

Publisher Summary This chapter presents experimental myocarditis (EM) experimental models. Two models of EM have been prepared in mice. The first was produced by infecting inbred strains with a cardiotropic strain of coxsackievirus B3 (CB3). The model was designed to simulate the broad spectrum of pathological changes seen in humans with virus-induced myocarditis. The initial phase of myocarditis is associated with the presence of infectious virus and is characterized by focal necrosis and infiltrates of polymorphonuclear and mononuclear inflammatory cells. During the later phase of disease, there is a diffuse mononuclear cell infiltrate and evidence of myocyte injury without significant myocyte necrosis. A feature of the second, autoimmune phase of CB3-induced myocarditis is the production of autoantibodies to the heavy chain of cardiac myosin. The immune response and the histopathological changes resulting from myosin immunization closely simulated the later phase of CB3-induced myocarditis. Susceptibility to experimental myocarditis is genetically determined, but genetic control of early disease differs from susceptibility to the late phase.