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Graft-Verses Host (GVH) Disease
Background
Human GVHD occurs after allogeneic stem-cell transplantation, with features similar to those observed in animal studies. Acute GVHD describes a distinctive syndrome of dermatitis, hepatitis, and enteritis developing within 100 days of allogeneic hematopoietic-cell transplantation (HCT). Chronic GVHD describes a more diverse syndrome developing after day 100. The majority of patients at risk for GVHD are bone marrow transplant recipients, but other transplant patients can also develop the disease, including the recipients of unirradiated blood products. The overall grade of acute GVHD is predictive of the patient’s outcome, with the highest rates of mortality in those with grade IV, or severe, GVHD. The response to treatment is also predictive of outcomes in GVHD of grades II-IV. Patients with no response or with progression have a mortality rate as high as 75% compared with 20-25% in those with a complete response. In chronic GVHD, mortality rates are increased in patients with extensive disease, progressive onset, thrombocytopenia, and HLA-no identical marrow donors. The overall survival rate is 42%, but patients with progressive onset of chronic GVHD have a survival rate of 10%.
Mouse Model for GVHD
The acute mouse GVHD model in mice has been used to determine the protective properties of experimental compounds. In this model, mice receive a lethal dose of radiation, given in 2 fractions on day 1, followed by autologous bone marrow and splenocytes on day 2. The radiation results in ablation of the host mouse marrow, and mice that are not successfully engrafted will die within 14 days. Mice that are successfully engrafted develop GVHD as the grafted marrow cells populate the host. These symptoms usually appear from day 10 onwards, and are scored on the scale shown in the table below. Endpoints are survival, GVHD score and weight change.
Table :Assessment of GVHD in Mice
| Criteria | Grade 0 | Grade 1 | Grade 2 |
| Weight loss | <10% | >10% to <25% | >25% |
| Posture | Normal | Hunching noted only at rest | Severe gait impairs movement |
| Activity | Normal | Mild to moderately decreased | Stationary until soft food is placed in the cage |
| Fur texture | Normal | Mild to moderate ruffling | Severe ruffling/ poor grooming |
| Skin integrity | Normal | Scaling of paws/tail | Obvious areas of denuded skin |
Asthma
Background
Asthma is a chronic inflammation of the lungs in which the bronchii are reversibly narrowed. Approximately 7% of the population have asthma and is estimated to affect 300 million people worldwide, and contributes to 4,000 deaths per year. During attacks, the airways become inflamed and constricted, making breathing difficult. Attacks can be prevented by avoiding environmental triggers, and are treated with beta-2 agonists and inhaled corticosteroids. Leukotriene antagonists can also be effective and antibodies to IL-5 and IgE can also be used to treat asthma.
Animal Models of Asthma
In murine model of asthma, mice are induced with ovalbumin, in combination with an appropriate adjuvant and sensitization schedule protocol. Following sensitization, mice are exposed to an aerosol of ovalbumin by inhalation or to ovalbumin given by intra-nasal or intra-tracheal administration. Evaluation of efficacy is based on histology, inflammatory biomarkers, cellularity of the BAL fluid and pulmonary resistance and compliance.
Aphthous Ulcer
Background
Aphthous ulcers, also known as canker sores or aphthous stomatitis, are oral ulcers – painful sores inside the mouth or upper throat caused by a break the mucous membrane lining the oral cavity. Aphthous stomatitis is characterized by recurrent discrete areas of ulceration that are generally painful. Recurrent aphthous stomatitis affects approximately 10% of the population, and many patients report a family history of the disease. In a cancer treatment setting, rapamycin and some drugs of the mTOR inhibitor family can increase the incidence of aphthous-like lesions in the mouth, which can become significant complications in patients who are neutropenic.
An Animal Model for Aphthous Stomatitis
Rats fed a zinc-deficient diet and treated with rapamycin develop aphthous-like lesions of the soft palate and tongue that can be evaluated, scored and photographed with an endoscope, or evaluated histologically.
Fibrosis
Fibrosis can be a long-term consequence of inflammation, particularly chronic inflammation. Asthma and other lung diseases can cause pulmonary fibrosis over time, leading to a permanent reduction in pulmonary capacity. Patients with inflammatory disorders and infection of the kidneys (nephritis) may develop fibrosis of the kidney as a consequence, and this is also seen in patients with nephrosis and nephropathy, side effects of diabetes and obstruction/inflammation of the ureter.
Animal Models for Fibrosis
Radiation Induced Fibrosis of the Hamster Cheek Pouch
Fibrosis of the hamster cheek pouch is a long term consequence of the radiation used to induce mucositis, and can be evaluated histologically four to eight weeks post radiation. Hamsters are anesthetized and the cheek pouch exposed and irradiated. Four to eight weeks later the extent of fibrosis is evaluated using standard histological stains (Sirius red, Trichrome) or immunohistochemistry.
UUO Model
Experimental Unilateral Ureter Obstruction (UUO) represents a model for obstructive nephropathy but also allows insight into the process of interstitial fibrosis that is a common characteristic of many chronic nephropathies. Markers of renal fibrosis, such as interstitial fibroblasts, interstitial volume, mRNA and protein expression for collagen I, are all increased in UUO animals, making the UUO model a good experimental system for studying fibrosis. In this model of fibrosis, animals are subject to UUO on Day 0 and the kidneys are removed (for histological assessment of fibrosis) and blood is collected on day 14.
Bleomycin Induced Pulmonary Fibrosis
Mice are anesthetized by inhalation of 2% isoflurane, and the trachea exposed by a cervical incision. Bleomycin in phosphate buffer saline is instilled intratracheally. Lungs are evaluated for evidence of fibrosis after 48 hours to 28 days post instillation. The trachea is ligated and lungs are inflation-fixed with 10% neutral-buffered formalin. Heart and lungs are removed and fixed, and stained with hematoxylin and eosin or Gomori’s trichrome to detect collagen.
