Drug Development in Pemphigoid Diseases

Pemphigoid diseases are organ-specific autoimmune diseases of the skin and/or mucous membranes. They are caused by autoantibodies targeting adhesion molecules located at the dermal–epidermal junction. While the diagnostics of pemphigoid diseases and insights into their pathogenesis have improved significantly, the development of novel treatments that are effective and safe remains an unmet medical need. However, numerous pre-clinical studies and early clinical trials have recently been launched. This review summarizes some pathways leading to drug development in pemphigoid diseases, namely: (i) hypothesis-driven drug development; (ii) omics-based drug development; (iii) drug repurposing; (iv) screening-based drug development; and (v) drug development based on careful clinical observations. Ultimately, it is hoped that this will lead to personalized and curative treatments.

TrkB gene therapy by adeno-associated virus enhances recovery after cervical spinal cord injury

Unilateral cervical spinal cord hemisection at C2 (C2SH) interrupts descending bulbospinal inputs to phrenic motoneurons, paralyzing the diaphragm muscle. Recovery after C2SH is enhanced by brain derived neurotrophic factor (BDNF) signaling via the tropomyosin-related kinase subtype B (TrkB) receptor in phrenic motoneurons. The role for gene therapy using adeno-associated virus (AAV)-mediated delivery of TrkB to phrenic motoneurons is not known. The present study determined the therapeutic efficacy of intrapleural delivery of AAV7 encoding for full-length TrkB (AAV-TrkB) to phrenic motoneurons 3 days post-C2SH. Diaphragm EMG was recorded chronically in male rats (n=26) up to 21 days post-C2SH. Absent ipsilateral diaphragm EMG activity was verified 3 days post-C2SH. A greater proportion of animals displayed recovery of ipsilateral diaphragm EMG activity during eupnea by 14 and 21 days post-SH after AAV-TrkB (10/15) compared to AAV-GFP treatment (2/11; p=0.031). Diaphragm EMG amplitude increased over time post-C2SH (p<0.001), and by 14 days post-C2SH, AAV-TrkB treated animals displaying recovery achieved 48% of the pre-injury values compared to 27% in AAV-GFP treated animals. Phrenic motoneuron mRNA expression of glutamatergic AMPA and NMDA receptors revealed a significant, positive correlation (r(2)=0.82), with increased motoneuron NMDA expression evident in animals treated with AAV-TrkB and that displayed recovery after C2SH. Overall, gene therapy using intrapleural delivery of AAV-TrkB to phrenic motoneurons is sufficient to promote recovery of diaphragm activity, adding a novel potential intervention that can be administered after upper cervical spinal cord injury to improve impaired respiratory function.

Gastrointestinale Stromatumoren (GIST)

Gastrointestinal stromal tumors (GIST) are rare causes of gastrointestinal bleeding. In most cases these tumors are localized in the stomach and small intestine, more rarely in the esophagus and colon.Pluripotent mesenchymal cells are the suspected origin of GIST. The pathogenesis is obviously initiated by gene mutations, leading to an overexpression and activation of tyrosine kinase proteins. This activation is followed by uncontrolled proliferation and loss of apoptosis. The immunohistochemical detection of the protein CD 117 (c-kit) is an important diagnostic tool. Activating c-kit mutations are observed in most cases of GIST. Grading of GIST remains a problem. Size and mitotic rate are the most powerful predictive factors associated with malignant behavior. The most common symptoms of GIST are pain and gastrointestinal bleeding. Endoscopy, sonography, scintigraphy or radiology -- enteroclysma, computed tomography (CT) and magnetic resonance imaging (MRI) -- are possible methods to detect a GIST. Surgical resection is the standard therapy of GIST. In cases of metastatic GIST, systemic therapy with imatinib, a tyrosine kinase inhibitor, frequently leads to partial remission and clinical improvement. Only few side effects are described. Five patients with GIST are reported. In all cases gastrointestinal bleeding was the main symptom. All tumors were surgically resected, and no signs of recurrence or metastasis have been observed in any of the patients so far (19-51 months postoperatively).

In vivo retroviral gene transfer by direct intrafemoral injection results in correction of the SCID phenotype in Jak3 knock-out animals

Efficient retroviral gene transfer to pluripotential hematopoietic stem cells (PHSCs) requires ex vivo culture in multiple hematopoietic growth factors (HGFs) to promote cell division. While treatment of PHSCs with HGF can render stem cells viable targets for retroviral infection, HGFs can promote differentiation, loss of self-renewal potential, and affect the homing/engraftment capacity of PHSCs. To avoid the negative impacts observed with ex vivo transduction protocols, we developed a murine model for in vivo retroviral infection by direct intrafemoral injection (DII), thus abolishing the need for removal of cells from their native microenvironment and the signals necessary to maintain their unique physiology. Using this approach we have demonstrated in vivo retroviral gene transfer to colony-forming units-c (CFU-c), short-term reconstituting cells, and PHSCs. Moreover, direct intrafemoral injection of Jak3 knock-out mice with retroviral particles encoding the Jak3 gene resulted in reconstitution of normally deficient lymphocyte populations concomitant with improved immune function. In addition, DII can be used to target the delivery of other gene therapy vectors including adenoviral vectors to bone marrow cells in vivo. Taken together, these results demonstrate that in vivo retroviral gene transfer by direct intrafemoral injection may be a viable alternative to current ex vivo gene transfer approaches.

Involvement of spinal tyrosine kinase in inflammatory and N-methyl-D-aspartate-induced hyperalgesia in rats

Phosphorylation of a subunit of N-methyl-D-aspartate (NMDA) receptor by protein tyrosine kinase (PTK) Src or Trk is known to enhance its channel activity. We examined whether a spinally administered selective PTK inhibitor, lavendustin A, which has high affinity for Src and Trk tyrosine kinases, could influence the development and maintenance of inflammatory hyperalgesia or NMDA-induced hyperalgesia. Inflammation was induced by injection of a mixture of carrageenan and kaolin into the tail base of rats. In another group of rats, hyperalgesia was induced by intrathecal administration of NMDA. Intrathecal administration of lavendustin A (1.0 microg) or NMDA receptor antagonist, (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cycloheptane-5,10-iminemaleate, MK-801 (3.0 microg) before injection of a mixture of carrageenan and kaolin or after the development of inflammation inhibited carrageenan-kaolin-induced mechanical hyperalgesia. Intrathecal injection of 1.0 microg NMDA produced thermal and mechanical hyperalgesia. Co-administration of 1.0 microg lavendustin A with NMDA significantly reduced the duration of spontaneous pain behaviour and inhibited NMDA-induced hyperalgesia. Lavendustin A itself did not cause any sedation, motor impairment or analgesia. Our results suggest that inhibition of PTK could be therapeutically effective as an analgesic in some NMDA receptor-mediated hyperalgesic states.

Inhibition of focal adhesion kinase (FAK) signaling in focal adhesions decreases cell motility and proliferation

It has been proposed that the focal adhesion kinase (FAK) mediates focal adhesion formation through tyrosine phosphorylation during cell adhesion. We investigated the role of FAK in focal adhesion structure and function. Loading cells with a glutathione-S-transferase fusion protein (GST-Cterm) containing the FAK focal adhesion targeting sequence, but not the kinase domain, decreased the association of endogenous FAK with focal adhesions. This displacement of endogenous FAK in both BALB/c 3T3 cells and human umbilical vein endothelial cells loaded with GST-Cterm decreased focal adhesion phosphotyrosine content. Neither cell type, however, exhibited a reduction in focal adhesions after GST-Cterm loading. These results indicate that FAK mediates adhesion-associated tyrosine phosphorylation, but not the formation of focal adhesions. We then examined the effect of inhibiting FAK function on other adhesion-dependent cell behavior. Cells microinjected with GST-Cterm exhibited decreased migration. In addition, cells injected with GST-Cterm had decreased DNA synthesis compared with control-injected or noninjected cells. These findings suggest that FAK functions in the regulation of cell migration and cell proliferation.