Objective Thrombin mediates the life-threatening cerebral edema that occurs following intracerebral hemorrhage. Therefore, we examined the mechanisms of thrombin-induced injury to the blood-brain barrier (BBB) and subsequent mechanisms of BBB repair. Methods Intracerebroventricular (i.c.v.) injection of thrombin (20 U) was used to model intraventricular hemorrhage in adult rats. Results Thrombin reduced brain microvascular endothelial cell (BMVEC) and peri-vascular astrocyte immunoreactivity –indicating either cell injury or death; and, functionally disrupted the BBB as measured by increased water content and extravasation of sodium fluorescein and Evans blue dyes 24h later. Administration of non-specific src family kinase inhibitor PP2 immediately following thrombin injections blocked brain edema and BBB disruption. At 7 to 14 days after thrombin injections newborn endothelial cells and astrocytes were observed around cerebral vessels at the time when BBB permeability and cerebral water content resolved. Delayed administration of PP2 on days 2 through 6 following thrombin injections prevented resolution of the edema and abnormal BBB permeability. Interpretation Thrombin, via its PAR receptors, is postulated to activate src kinase phosphorylation of molecules that acutely injure the BBB and produce edema. Thus, acute administration of src antagonists blocks edema. In contrast, src blockade for 2-6 days following thrombin injections is postulated to prevent resolution of edema and abnormal BBB permeability in part because src kinase proto-oncogene members stimulate proliferation of newborn BMVECs and peri-vascular astrocytes in the “neurovascular niche” that repair the damaged BBB. Thus, src kinases not only mediate acute BBB injury but also mediate chronic BBB repair after thrombin-induced injury.

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Bortezomib (Velcade®) is a proteasome inhibitor that has been approved for the treatment of multiple myeloma and mantle cell lymphoma. It has been shown to inhibit the expression of cell adhesion molecules, co-stimulatory molecules, and NFĸB activation, to deplete alloreactive T lymphocytes, and to decrease Th1 cytokine production. The anti-inflammatory effects of bortezomib were further investigated in this current set of studies. Systemic treatment with bortezomib was efficacious in the thioglycolate-induced MCP-1 production model, and the dinitrofluorobenzene-induced delayed-type hypersensitivity model. Psoriasis is an autoimmune disease that affects about 2% of the world population. Many treatments have been reported with varying degrees of efficacy. A topical bortezomib formulation was developed to minimize systemic exposure. Its tolerability was investigated in a topical imiquimod (IMQ)-induced psoriasis model. Daily application of IMQ on mouse skin induced inflamed scaly skin lesions resembling plaque-type psoriasis. Fatality was observed in the 1-mg/ml dose group. At 0.1 and 0.01 mg/ml, bortezomib potentiated IMQ-induced erythema, scaling, skin thickening, and caused necrotic lesions. Lower doses had no effect on the clinical observations. Histologically, bortezomib dose-dependently increased parakeratosis, hyperkeratosis, acanthosis, and inflammatory cell infiltration. This study demonstrated that topical bortezomib is not suitable for the treatment of psoriasis.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma affecting children and is often diagnosed with concurrent metastases. Unfortunately, few effective therapies have been discovered that improve the long-term survival rate for children with metastatic disease. Here we determined effectiveness of targeting the receptor tyrosine kinase, EphB4, in both alveolar and embryonal RMS either directly through the inhibitory antibody, VasG3, or indirectly by blocking both forward and reverse signaling of EphB4 binding to EphrinB2, cognate ligand of EphB4. Clinically, EphB4 expression in eRMS was correlated with longer survival. Experimentally, inhibition of EphB4 with VasG3 in both aRMS and eRMS orthotopic xenograft and allograft models failed to alter tumor progression. Inhibition of EphB4 forward signaling using soluble EphB4 protein fused with murine serum albumin failed to affect eRMS model tumor progression, but did moderately slow progression in murine aRMS. We conclude that inhibition of EphB4 signaling with these agents is not a viable monotherapy for rhabdomyosarcoma.

Embryonal rhabdomyosarcoma (eRMS) is one of the most common soft tissue sarcomas in children and adolescents. Parameningeal eRMS is a variant that is often more difficult to treat than eRMS occurring at other sites. A 14-year-old female with persistent headaches and rapid weight loss was diagnosed with parameningeal eRMS. She progressed and died despite chemotherapy with vincristine, actinomycin-D, and cyclophosphamide plus 50.4 Gy radiation therapy to the primary tumor site. Tumor specimens were acquired by rapid autopsy and tumor tissue was transplanted into immunodeficient mice to create a patient-derived xenograft (PDX) animal model. As autopsy specimens had an ALK R1181C mutation, PDX tumor bearing animals were treated with the pan-kinase inhibitor lestaurtinib but demonstrated no decrease in tumor growth, suggesting that single agent kinase inhibitor therapy may be insufficient in similar cases. This unique parameningeal eRMS PDX model is publicly available for preclinical study.